For gadget-enhanced tenting, I've started using AGMs in small form-factors (35ah, 14ah). Results so far have been very good, although I will say that a weak/worn out AGM is VERY weak.
Biggest difference to me is that these batts handle like dry cells. I transport them inside the car and recharge them inside the tent (very well ventilated). Can't speak to longevity yet, although I will say that AGMs are VERY pricey, and I'm using the cheapo UPG batts. I cannot imagine paying out for a set of Lifelines for the TT--I'll stick with the cheap Costco GC2s.