@BadWolf I never rode more than two. When ever I sold one I bought another and it went like that for about a year till they caught up to production and I couldn't do it anymore. So yeah... Never rode more than two before I sold one and started the process all over again... It was fun for awhile. Didn't make a ton but I did manage to pretty much pay for the two boards I own in profits. So yeah... Agree you don't need more than two.
So far I've been lucky (fingers crossed). I've left it locked up outside several restaurants while I eat, with no problems. This was in high-traffic areas where someone carrying bolt-cutters would certainly attract attention, and not for more than an hour or so. Also I'm sure @AdamDoubleG is right--no thieves probably know what the heck this thing is yet, much less what to do with one if they were able to get the lock off.
@Count to add on to what @njcustom said I have had one experience where I was on an extremely rocky offroad trail and somehow a very large rock stuck to the wheel and the wheel tried to keep spinning but the rock was digging in to it and eventually jammed. So it threw me about 5 feet in front of the board. If the tire had treads I could see this situation happening all the time. Just like your car tires pick every little rock and pebble up.