Your situation sounds nearly identical to me about 3 months ago, except I'm in the Appalachians. I ultimately decided X YBB was the way to go, though admittedly I never test rode an XZ. But for me, I need great climbing, and just enough of a thud buster in the rear to keep me going all day. I've done full-susp in the past, and though it's a plush ride, a lot of energy can be lost if your up & down all day. If I could convince the wife that I needed yet a 3rd bike, an XZ is definitely next on the list.
Word of advice, if you're buying new, think custom geo. I'm about an inch taller than you and bought an off-the-shelf 18" X YBB. While the standover is pushing my 32" inseam, the top tube length at 23" is a bit too short. Should be around 23.5 - 23.75 to give a little more proportionality IMO.
ti Nuke Proof
ti Moots Mooto X YBB