I've got a 2012 XU that my wife commutes back roads to work on (well, my wife owns & rides it, but I keep the household's motorcycles going, so I'm responsible for the Zero). I'm coming to this from a history of Eurobikes too. My current commuter bike is a 1981 Morini 500. Picked up the 2012 XU during the "cash for carbon" deal earlier this year.
Our family's experience with the XU is that your airheads are much more reliable. An old Morini is more reliable for that matter.
We got ours late March. Had it 4 days and the horn stopped working. I traced it to the horn itself, took Zero 2 weeks to send out a new one. Late June the bike stopped dead a couple of miles from home, I managed to get it working long enough to get home. Then it stopped completely. My wife said it sounded like something in the throttle assembly went click - so I emailed the dealer we got it from to send me out another throttle assembly. The dealer, btw, is 120 miles away, and our nearest dealer. (I pointed out that as I'd just fitted a completely new ignition system to the Morini, I was probably up to fitting a new throttle assembly). This coincided with us heading overseas for a while, so the bike sat for a couple of months.
It took me a while to get back to it, and when I did, folks at the dealer said as a warranty job, they'd have to do it and couldn't send me the part. I tried to get the head of their service dept for a chat, we did the phone tag thing a few times, and never caught up. In the end I gave up and - we don't have a truck (carbon accounting?), and hiring a truck wasn't cheaper enough, by the time I included the 240 mile round trip - so the dealer came & picked up the bike. They've got it fixed pretty quickly - just under 2 weeks from it being picked up (today) - and now we just have to get it back. Guess we'll just pay for the dealer to transport it. Our transport costs for the warranty work will be the same as what it just cost me to get another bike's frame straightened.
My sense of our issues - some of the components used in the Zero XU are unreliable, and there's a good chance that they're going to stop working. They may be very cheap components leading to problems that - were they to occur in an out-of-warranty internal combustion engined bike - you'd resolve yourself easily (fork seals for instance). Less the case with a Zero. If you're some distance from a dealer you need to decide for yourself how you're going to deal with the hassle of getting the bike to your dealer, or arguing about doing the work yourself and then doing it (no Haynes/Clymer manuals for these). Presumably with an airhead, you've got experience working on motorcycles.
And we still don't have a second key, or the key details (so we could get a key if we lose the one we do have), for our XU despite nagging - both the dealer and Zero - since the day the bike was delivered. Make what you will of that.
The XU is a great idea, and when it works it's really lovely to ride. Comparable power to a CB100 or equivalent (XL125?) for anyone who remembers those old bikes - but with better brakes. Zero need to get their quality control act together on their components.
fwiw
Peter
PS hi folks.