I thought the shock spacer simply returned the up & down part of the shock to its normal range. Not sure how they make for more down travel then normal. Good to know about the CV boots rubbing.
On the rear reading up on the install of rear shocks it seems a lot of extra pressure is needed up on one end & down on the other end to remove the coil. Can wheeling really reproduce this & cause the shock to fall off. Also I don't think the rear shock spacer adds any space to the rear spring area that holds the shock. The install instructions I've read on the rear never mentions needing extended brake lines. Just to be careful as you manually compress one side it pulls on the brake lines.
You are correct in that it moves the hydraulic ram back towards the middle of its stroke - but it does that by adding an inch to the over all length from mount point to mount point (the height of the spacer). This increases the distance the suspension can travel when unloaded, which is your down travel.
On the rear, we didn't find that a ton of pressure was needed to get the springs in and out, honestly. The king springs are shorter than the OEM springs, and the spacers make the struts longer. Whether you could convince them to come out while wheeling, I don't know. I also doubt it, but they're certainly not as solidly in there as the oem ones where.
I did all this on a lift, so the suspension was at
full droop on all four tires - IE the only way you could replicate these results in the real world is if you take your 100 airborne. I haven't yet had a chance to really flex it out and see if the sway bars are stiff enough to avoid the 'contacting the strut bodies' problem that I noted. Also, if you ever have your car worked on, they'll likely lift it off the ground and all four wheels will hang - if you don't prepare for that, you could break a brake line or dent your struts.
Obviously, YMMV and what you do to your truck is totally up to you. I imagine replacing the front upper control arms would solve the strut contact problem ($$$), and longer rear sway bar endlinks ($) and/or removal of the rear sway ($free) would solve that same issue on the rear. The brake line problem I simply solved by bending the brackets (this is for the center line that splits at the rear axle, not for each brake at the caliper), but I'll be getting myself some slee braided lines sooner rather than later.
Edit: been musing over this for a while, and I've pretty much determined that I want to keep AHC indefinitely. The only time I think I'd want to remove it is if I ever got to do a very long-term and/or remote trip where an AHC failure could be catastrophic. AHC is just too dang useful as a load and stress leveling system.
For example, I've read several threads/stories of folks that have broken their lower control arms thanks to wheeling with heavy loads and stiff T-bars. I'm willing to bet that it's a non-issue for AHC owners because the weight of the vehicle is spread between the T-bars (and their mounts on the control arms) PLUS the AHC system. In other words, the control arm t-bar mounts only see about half as much force under normal use in an AHC equipped truck vs conventional suspension. Same logic applies to the rear, although I have not heard of any load failures from the rear end. Also, the auto-leveling while towing is a really nice feature, completely avoiding the possible installation of air bags.
Even better - I'm able to upgrade to OEM t-bars and probably springs while still maintaining the advantages of an AHC equipped LC.
There are a few disadvantages:
* repairs to the system generally aren't cheap (but neither is all new suspension components)
* it's a huge step up in complexity vs conventional suspension
* have to put some work into figuring out who makes front control arms that are compatible with AHC
* AHC spacers reset the neutral point of your suspension, but don't increase your travel IE a conventional suspension upgrade can have more travel vs AHC
