Are you expecting the camera to run continuously for months or years on end ? Or power up and down based on some external input ?
In the former case, I would expect problems. The millisecond timer from get_tick_count will wrap to negative in ~25 days, and back to zero in ~49. Aside from that, there could well be other counters or resource leaks that eventually kill things. Neither the original firmware nor CHDK are built with the expectation of long uptimes.
What sort of events would you want lua to support ? Feel free to add suggestions here Improving the lua interface
Moving to a more event-driven model is definitely a possible future direction, although probably not near future