Got 'em all. The X1 is nice, but the last I reach for because I have had some of the "less than positive" activation behavior of the momentary switch, and it is the biggest of the three. I am a big Gerber IU fan, and now with the latest ones coming with CS LED's, you don't have to mod it to make it great. Runtime is the best of the bunch, although the X1 is fairly close. Also like the tailstand ability and clip to put it on my hat brim for hands free use. While not advertised, the tailcap performs flawlessly (on all of mine) in momentary mode, just by virtue of the play in the threads.
The only reason to go for the slightly less bright E0, since they are all close in price, is size/weight. It gets a lot out of a AAA at the lower drive level, but won't make up for the huge capacity of the AA in the other lights. But as an old backpacker who has gotten by using Solitares to save weight, this thing totally rules when size and weight are big factors. I use a light mostly for digging in the packs at dusk and in the tent. But if I got stuck on the trail after dark, once it was REAL dark and my eyes were not spoiled by twilight, I could hike all night by an E0 without tripping over roots and rocks. Little lights look a lot more impressive out in the woods.
Hondo