Never rebase. Adapt the rules to your figures, not the other way around.
20 years from now, I will be using rules that most likely have not been written yet, with novel concepts yet to be invented. But I know that many of my current figures will still be used 20 years from now.
Hence, rules should serve the figures; the figures should not serve the rules.
Tiny Tin Men Blog: http://snv-ttm.blogspot.com/
Wargaming Mechanics Blog: http://wargaming-mechanics.blogspot.com/