If I could do it over again, I would've just ditched the IFS and done an SAS but that's just me.
But yes... everything is truly dropped 6". The only reason I'm cranked at all is to level it with the rear... I'm getting some longer shackles here soon to drop the rear some then I'll take the crank back down to 6". Fresh out of the box, installed, and everything set at 6", all of my angles were as good as they could be.... CV's were completely flat, etc. Like I said earlier, even with it cranked a little bit now, my angles are still better than they were when my truck was stock and cranked. Also, it clears 35's just fine with 17x9's with a 4.5" backspacing. I could clear 37's without any problems with the way it sits now though (yes, I've actually tried it with a buddy's 37" KM2's) but 35's will still clear just fine when I take the crank back down to 6".
I've had my Pro Comp for 5 years now and nothing has gone wrong with the kit itself. I did however rebuild my front end while I was in the process of installing it though (i.e. new bushings, ball joints, hubs/unit bearings, pitman/idler arms, blah blah) and all of that stuff is still good. The only thing I've had to touch on my front end after the kit was installed has been my CV's because my boots had started to rip and they were slinging grease everywhere but I reckon that can be expected from 20 year old CV's. I just replaced the whole CV shaft when the boots failed and haven't had to touch a thing since. Just be sure to keep the greasable stuff greased up periodically and you should be good to go.
IMHO though, go with 17x8's over the 16.5x8's. You'll be happy that you did if you ever choose to get a tire other than Ground Hawgs or Super Swampers.
Also, if it sounds like I'm trying to suck Pro Comp's d*ck here then that certainly isn't the case.... I'm just giving my experience with what I have.
Cheers and good luck friend.
Zach
Edit: Just for fun, here's a couple of trucks with 6" Pro Comp's and 37's.
37" Baja Claws on NBS (or NNBS?) stockers:
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37" MTZ's on Moto Metal 17x9's 4.5" backspacing:
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And a couple of mine just for reference without any crank, and 315x70x17's (35x12.50's) with 17x9's 4.5" backspacing:
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