Z-20: What else can I expect to go wrong?

A question for those with EV experience: given the many discussions of various problems that have occurred with the Z-20 scooters, as a Z-20 owner (#29 arrived January 4th 2008), what major components should I, a total EV newbie, be concerned about?

As far as I know, my Z-20 is fully functional, but being located in southwest Michigan, I’ve only had it out for a short, low speed ride when it first arrived. I’ve taken off enough of the body to get at the electronics and verify that I don’t have issues with pinched/frayed wiring described in one of the earlier posts (http://visforvoltage.org/forum/2576-evt-z20-arrived-pics-and-impressions), and to start the process of conditioning the batteries and wiring for bank charging. Weather permitting, I should be able to start riding in a few weeks, and as I read more topics on this site, I get more concerned that I need to prepare for major rework.

From the post http://visforvoltage.org/forum/2864-z20b-teardown, I plan to add a contactor ($90). From that same post, it would seem that controller design is, shall we say, sub-optimal and may need an upgrade ($350 and up). I’ll also probably bypass the alarm as described so that it isn’t in the circuit between the throttle and the controller.

I understand that there are several add-ons that I could implement to improve the scooter that are advisable (bank charging, Pak-Trakr, Cycle Analyst, LiFePo4 batteries, etc.) but I’m currently concerned about those things that will suddenly go kaput and leave me stranded.

The warranty states that an unused scooter can be returned for a 30% re-stocking charge; assuming I could or would return it, I’m out about $600 (let’s assume for the moment I’m playing by their rules and not trying for a full refund). For the same $600 dollars, can I modify/upgrade the critical components and have a scooter that the experts here would deem a reliable scooter?

Beyond the contactor and the controller already mentioned, what components could I typically expect to have problems with, and what would the associated cost be? (Let’s assume that I can handle most labor myself, assuming it doesn’t require specialized training or tools). I would expect that the motor would be the last major component that hasn't already been discussed, but I'd appreciate it if someone could elaborate on that and anything else I might be missing.

Thanks for all information you’ve already provided; hopefully I’m not asking you to repeat yourselves needlessly.