Not to write an essay or anything, but I have nothing else to do.
My truck has embarrassed my buddies WJ multiple times. And I literally mean multiple times. My truck has also embarrassed my other buddies XJ's (he has had about 8 and build's them for a living.)
Solid axles make a much rougher ride. The unibody construction is horrible on these things. When off roading you can hear and feel the body twisting, not that it's going to fail, but its still super annoying! Whenever I drive their's I feel as if something is going to break (and they often do break stuff) which to me at least, a serious confidence killer. No wonder Jeep drivers drive so slow. Really. The lighter weight of the Jeep will make it harder to get traction on harder dirt, or even light mud.
The Jeeps system will allow the wheels to spin more freely. This advantage would be better for deep mudding, or going in the clay pits as you guys plan to do. Again the Jeep is lighter, so in heavy mud/clay/whatever, it wont sink into the ground surface as easily. The 4.0 engine is bullet proof, though you're buddie has the V8. My friends have had both. Even though the 8 is up on power a little bit, they both like the 4.0 more. At least compaired to the 4.7.
Deep mudding will not be as good do to heavier weight as the truck will sink into the groud more. The all independent will have very poor articulation compaired to any solid axle vehicle. (But thanks to the anti-lock brake control, who cares.)
First thing is that the Explorer is a much better overall built truck then the Jeep. I said the all independent suspension will hurt it in the articulation department, and it will, so what. It doesnt need great articulation. As I hope most of you know by now, the anti-lock brake control system is great on these trucks. Especially when you upgraded the diffs with Torsens. At this point the Explorers system is equal to Jeeps quadra drive. Whenever a wheel becomes airborn and starts spinning, the system stops that wheel and the power has no where to go but to the grounded wheel. The wheel with traction. The all independent suspension makes a much smoother ride then the Jeeps. The frame on these trucks have zero flex in them. Even when on the most extreme articulation situations. It just feels so much more solid, because it is. That and the suspension makes you feel as if you aren't even off roading. All my friends comment on this! Because of this you really have to start driving fast to push the truck. When the whole gang goes off roading, or if we go out on meets, my Explorer and my buddies Explorer always check out. We literally have to stop every 5 minutes and wait for everyone else to catch up! On tight curvy dirt roads the independent suspenion takes the corners much better. As far as weight goes, the Explorer will have more traction on hard dirt roads, or light mud.
All and all, the trucks have their pros and cons. Sure, his truck may be just slighty better in the mud and clay. Who cares.
You have a truck that is so much stronger (which I have never broken a single part on my truck BTW, whereas my buddies do break stuff on their Jeeps left and right, and I drive twice as fast!) handles so much better, your truck is so much smoother, has a smarter computer system, and much more controlled driving dynamics over all. The Explorer is built and engineered to a leauge that is so far out of the Jeeps.
P.S. My buddy wants to trade his truck for a 4th Gen.