Glacier, I've got some answers to a couple of questions that you have had -
"I am still mystified why the 5R went from a 3 plate OD clutch to a 2 plate, and from a 6 plate forward to a 5 plate forward clutch."
I'm sure you have the charts that show what is applied for which gear, but for the benefit of the reader, I'm going to list which clutches are engaged when you are in a certain shifter position (not including one-way clutches, sometime referred to as "sprags").
In Overdrive (D-Circled):
1st - forward
2nd - forward and intermediate band
3rd - forward and reverse/high
4th (OD) - forward, reverse/high, and overdrive band (not OD clutch)
In Drive:
1st – OD, forward
2nd - OD, forward, and intermediate band
3rd - OD, forward, and reverse/high
So, in the OD shifter position (the position the shifter is in 99% of the time normal on-road use occurs, not including towing or 4x4'ing), the OD clutch is disengaged (frictions slipping against steels, or more to the point -with a thin layer of fluid between them). By reducing the number of plates, it is true that you reduce their longevity (after all, there is less friction material), but this is a tradeoff for fuel economy. Fewer layers that aren't moving at the same speed (as in a clutch pack that is not applied) equals less viscous loss (viscous drag), which leads to more power getting out the back of the transmission. I have a feeling that is also part of the reason why you see that they went to a spiral-grooved pattern on the friction plates. The grooves not only allow for more fluid to cool the plates, but also has two other benefits: 1) less resistance when the clutch is being applied because it allow a pathway to get the fluid "squished out" and out of the way (more positive application), and 2) when the clutch is NOT applied, it keeps a thicker (not more viscous "thicker", but physically more distance "thicker") film of fluid separating the plates, which also decreases the viscous drag effects of the plates not spinning at the same speed.
For highway driving (OD position on the shifter), you can see that the OD clutch is NEVER applied, and since this is how they get their EPA mileage ratings (also looked at by many consumers when purchasing), fewer plates was/is a GOOD thing. I hope that answers why they went to a 2-plate OD clutch design. The ONLY drawback is when PEOPLE start to shift from D to OD (to pass or whatever), because THAT will cause the application of the OD clutch (more on this later).
Now to answer your second question about why they went to a 5-plate design on the forward clutch. The forward clutch is ALWAYS applied in ANY gear, ANY shifter position except for Park, Neutral, or Reverse. This means that almost all of the time this clutch is applied and should be holding (not being engaged and disengaged). The holding force is not determined by the area of the clutch plates, but rather by the pressure forcing the plates together (line pressure times the area of the piston) and the makeup of the friction material (its coefficient of static friction). To make the holding power of this clutch pack increase, more pressure in the piston would be required. As for why make it fewer plates, again this is a fuel economy issue. Fewer plates means less rotating mass to accelerate and decelerate (either by engine acceleration or by the application of other clutches by changing of gears). This also leads to longer life of the other parts of the transmission. If the clutch is always engaged, there isn’t much to be gained by having more friction material. Now boosting the line pressure to this clutch pack could lead to more holding power, which could be a good thing. Let’s just agree that “Neutral Drops†(going from a high-RPM neutral to OD) are NOT a good thing for the forward clutch, as this is the only “soft†clutch that gets applied.
So, where can WE make improvements to our A4LDs to make them last longer? The #1 major concern should be maintaining good line pressure in our system. This will keep the clutches and bands from slipping. The source of the pressure is the pump, and the best you can do is new. The pump is a gear pump and over time the gears get more and more worn away, leading to increased tolerances and lower possible pressures. This is why I am strongly considering putting in a permanent line-pressure indicator (will update this when I get it done). Now besides keeping the pressure high from the source, we need to do everything possible to eliminate the leaks that cause the pressure seen by the clutch pistons and servos (for the bands) to be lower. The things that immediately come to mind are 1) valves fitting tightly (low-tolerance) in the valve body (or, like the booster valve Glacier is using, o-rings), 2) good seals on all of the clutch pistons and where those pistons get their pressure from (rotating seals), 3) good seals on the servos, and 4) clean fluid passages (even through restrictions like the 3-4 solenoid), and 5) other rotating seals such as the front pump seal (prone to failure) . CHANGING THE FLUID will add to the life of these things by removing the tiny particles of friction material (normal wear) that can wear away the rubber in the seals, creating minute leaks and lowering the pressure (force) felt by the clutches and bands. Of course, adding extra beefiness to supports and using Torrington bearings instead of thrust washers will add to the seal life (rolling bearings wear slower than sliding bearings and thus release less seal-killing particulate matter into the fluid). High temperatures also kill rubber, so adding coolers can also improve the life of the seals. - (after writing all this stuff about saving seals I feel like clubbing a few baby seals so that the Tao, Yin-and-Yang, of nature is preserved
)
All of these things are good (even great) ideas to increase the life of the transmission, but it doesn’t change the fundamental fact that the friction material on the clutch plates and the friction material on the bands are of finite thickness. This leads me to the #2 major concern – conserving friction material. There is only one thing that can conserve friction material, and that, I’m afraid, is how/where you drive. I live in the mountains and drive in OD on mountainous highways – thus I had a lot of 3-4 automatic shifts (passing). The thing that failed was the OD band (which is the only thing that changes from 3rd to 4th while in the OD shifter position). Because of this wearing away of the OD band, it failed and then other things got messed up, but I know now that it WAS the OD band. What I’m trying to say is that driving habits can greatly influence how long the friction material lasts. People that drive around or tow in Drive and drop into passing gear (2nd) might find that their intermediate band is the thing that failed, or people who “Neutral-Drop†might find that the forward clutch is burnt up. It just depends…but one thing is certain – the friction material WILL eventually run out, and when it does, hard parts can get seriously screwed up because they are dealing with things for which they weren’t designed.
So my final thoughts are contrary to many who say “don’t fix what isn’t brokenâ€â€¦.fix it BEFORE it breaks. You will feel better about the reliability, and possibly save some $$$ in the process (soft parts such as friction plates, bands, and seals are MUCH cheaper than the hard parts).
, but remember how you were singing their praises not too long ago, and they probably aren't a resource that you want to have mad at you. 
