Watch the video on this page... explains how quick lift works
http://www.strutmasters.com/Explorer-Rancho-QuickLIFT-p/rs999781-1.htm
Hahahaha site says we can clear 35"'s with quick lift... seems like they've never measured the wheel well...
Looks like a great SAFE way to lift plus you can wirelessly control them with add on...
Seems like the controller/adjustment is more for changing the valving, or the stiffness, of the shocks themselves.
It did mention that the gain in height is due to a different height of the spring seats.
This sounds to me like the way a coil spring spacer works (not strut spacer, like the BTF type)
Basically it goes between the coil spring and coil spring seat (with the strut disassembled) and it takes up space in there...keeping the coil from compressing as much. The lift comes from the fact that the truck's coils can't compress as much when the truck's weight rests on the suspension...so the truck sits higher.
The upside of this is that the shock still has the same downtravel as stock...so it tops out before the control arms/spindles interfere with the coils (as what happens to a lot of people with BTF spacers when the suspension travels downward far enough). Your control arms would still be angled as with the BTF spacers. How much depends on the size of the coil spring spacer.
The downside with a coil spring spacer is that up travel is affected...the spring can't compress as much as it could stock. How this would affect ride quality on an OEM strut probably depends on how big the coil spring spacer is. I suspect that the Rancho setup is supposed to let you adjust the shock itself to compensate the ride quality for the loss in up-travel.
There would be a limit to how big of a coil spring spacer you would put in...if you went too big you could ultimately take away your up travel to the point where the ride would suck. Again, I think the Rancho setup has tried to address this by keeping the coil spacer size they use mild and softening the ride with changes in shock valving.
The only other downside of coil spring spacers or rancho quicklift assemblies would be that it looks like you have to disassemble your strut and use a coil spring compressor to install the coil spring spacer (or the shock itself with the rancho).
Might be worth researching coil spring spacers to see if you can just get the coil spring spacers without the rancho strut. Would be cheaper but hard to say what the effect on ride quality would be without somebody trying it. I might give it a go if I can find the right parts.
You could do this with BTF spacers but I would think they'd need to be small enough to keep the spindle from hitting the coils in the front and the axles from touching the frame in the rear. Currently with 1.75" in the front and 1.5" in the back my spindle does touch the coil at full droop and the axleshaft does touch the frame. It only happens when the wheels are completely off the ground though. Still plan on doing limiting straps to fix that.