I like my serpentine belt. Trail or daily driving. You can talk all you want about alternator bearings siezing up or any other accessory failing, fact is these parts don't just fail without first screaming or making other noises. If I take off and hear my Alt singing to me and it fails on the trail, shame on me. Same goes for the p/s, a/c or tensioner. These parts don't just instantly lock up without warning very often (if at all).
Fact is the OEM's have spent millions of dollars designing the serpentine setups and spent countless hours and miles in durability testing. As long as the accessories of good quality (no cheesy bottom feeder reman parts) and are in good working order the chances for failure are no more than the same parts with a v-belt on it.
Yes there is no way to deny the fact that if one part fails it can shut everything down. I realize that fact and make sure my stuff is ship shape before I leave to minimize any chance for failure. Yes I carry a spare belt on the trail. Have I needed it yet, no. Still take it with me along with tools and other spares. Being prepared for anything I guess.
As for belt slippage, never had it on this setup. On the alignment issue, if you use the factory GM brackets the only pulley that you can even move in or out is the p/s pulley. Heck you can even use your old p/s pump you just have to press the serp pulley on, just use a straight edge to line it up to the other pullies. If one wanted onboard air, Kilby has the brackets to install a york in place of the stock a/c compressor (using the serp belt) or install it beside the alternator and run it off of the alt with a v-belt from a combo v-belt/serp pulley on the alt.
Each setup has it's positives and negatives and it boils down to personal preference. Like I said, I like mine. When I had to replace my leaking water pump recently all I had to do was remove the fan, then the belt, the lower hose and then the 4 bolts that hold the pump. took 15 minutes to get it out and I was working in the dark (no driveway lights

) with only a flash light. Never had to touch the other accessories like I would have on a v-belt setup (and set tension on 3 belts later!). Every other accessory is just as easy (the p/s pump is the hardest, no harder than the v-belt) and the best part is, ZERO adjustment. Bolt on and install the belt. No more Alternator belt adjustments coming loose (causing slippage and low charge), no more need to buy 3 belts for spares, no more flipping or chucking belts at high engine rpm.
Run what you want, I say.