I agree... these numbers are not out of line at all for UL. I have friends who use Exos 48s and their weights are similar to mine (with Arc Blast) because the shelter/food/cook kit weight is split. We recently did a 4-day trip and all our pack weights were well under 20 lb (15-16 in fact) which included 1 liter of water each for them, 20 oz for me.

I too rarely carry more than 1 liter, although there can be some significant dry stretches here in the NE in the summer and fall that require carrying more.