Yes that's the one.
Almost all of the 6-7 inch lifts are really 4-5 inch diff drop/knuckle lifts, that then crank up to the max height to make that marketable number.
The limitation stock, is not the amount of height available to adjust via the torsion bars or via that coil over option. it's the limitation of the CV axles.
Cranking the bars, adding those coilovers, etc. will all do the same thing (except the coilovers will ride nicer). They both change the cv angle for the same given height, because the diff stays still. If you are talking about 2-3 inch crank stock or with keys (or using those coilovers) your CV angles will suffer. (To answer the question on the first page of the thread, yes cranking to 3" in the front is possible, but not a good thing, the CV's will break.)
That is why, I think, a diff drop lift kit like the RCX, de-leveled as much as possible, which will give you ~4 inches of lift, would be your best option, as you get the height, but not too much, and most importantly at 4 inches of lift you CV axles will be at a stock, or better, angle as the diff is dropped the 4 inches added on the hub/knuckle side. With the 2-3" of lift from the crank or coils you are talking about without your diff dropped, your CV angles will be hurting.
My vehicle spends ~20% of its mileage towing an 18 foot 6000lb trailer, and does fine, with 33's (285/75/16) and 5.5 inches of lift. With smaller tires(if you go to 33's or bigger I'd recommend 4.10's, but this isn't caused by the lift options, just the tire size) and the lift only set to ~4 inches your truck will tow great. 4-5 inches of lift on these trucks, with how big they are, doesn't make too much of a difference. Even with my 5.5 and 33's i am barely taller than some of the 2500hd's.
Just wanted to let you know my experience. I originally got the cranked kit thinking I was going to get 2 or 3 inches, which I then learned off road, was going to be unreliable, so I decranked it to 1.5" and just enough to fit 33's and lived with it for 3 or 4 years. I then moved to the RCX 6". In retrospect, could have saved the $400 from the crank, and put it towards almost half the cost of the RCX.
Edit:
Options as I see it:
Option 1: Crank/coilover 1.5" to get some but not all the stance/ height or fit larger tires with Decent CV angle ($400)
Option 2: Crank/coilover 3" to get stance and height you want, but with bad CV angles ($400)
Option 3: Diffdrop/ knuckle 6" kit, de cranked to 4" to get the stance and height you want with perfect CV angles ($1000)
Option 4: Diffdrop/ knuckle 6" kit, cranked to 5.5" to get a taller stance and height with decent CV angles ($1000)
Any inch of ground clearance you can get for these things off road is gold, and you aren't sacrificing too much ride quality wise (actually the ride will be better with a decranked lift as the torsion bars wont be cranked as much for the given amount of lift, so won't be as stiff) so towing won't be hurt much, if at all. (Actually my suburban tows better with the lift than the crank, but that may be because I added the $50-100 kicker bars and steering stabilizer, and got an alignment after install, which was it's first in 30k miles.) The cost isn't too bad either, i just don't want someone else in a similar boat to me, make the same mistake of having to spend the money twice.
Hope it helps, I was there a few years ago and it's all a tough choice! I know everyone's got different uses, but ours seem very similar being some tow vehicle, some adventure vehicle.
