Well, the necks do feel quite different, the RG is going to be skinnier than the Legacy. If you like strats a lot, getting the Legacy and modding it to your liking could be a good idea. Also, are you planning to do a lot of whammy bar work? A double
locking bridge like on the RG can't be beaten for that.
Also, did you consider the G&L S500? I understand it is a strat with slightly more modern features than the Legacy.