Metal Cloak GC 2.5" owner here.
If instructions are followed correctly, you will neither rub a fender off during up travel (on either the 2.5" or 3.5" lift) nor will you rub your drive shaft during articulation.
Assuming you're purchasing a kit with adjustable control arms, you need not worry about caster (whether it be a 2.5" or 3.5" lift).
Your shocks are the limiting factor of articulation. IF you only change the spring height and not the shocks, nothing will change in in total downward articulation; Only how up travel and down travel are distributed (unless you add more/less bump stop to the springs or add articulation limiting straps).
So if you're raising your rig 1" higher at ride height, you gain 1" of up travel, but lose 1" of down travel.
The MC kits are the premium of kits. Everything has been engineered correctly to ride with no major issues. Whether you have stick fenders (or not) the kit will not run fenders on upward travel, nor rub a driveshaft during downward (assuming you're off-roading under normal conditions and not taking jumps).
*There is no issue of caster, if you're getting adjustable arms, and I'll double check tomorrow, but I believe the 2.5" lift with 35s requires 3 picks in the rear (I'll double check tomorrow).
*Also, keep in mind Metal Cloak lifts run higher than advertised. They take into accommodation that your rig will be outfitted with winch, or rack or whatever...
And as someone suggested, if you're going 3.5" you'll need their high steer kit.