Height limit is already pretty low... 40" I think? I don't see it being lowered any more than that. At some point restraints stop restraining people...
As for the lapbars, I remember someone (a CM, I presume) posted on here the last time the discussion came up, and they'd sat in the new log backstage. They said that there really wasn't a change in legroom, and for some people there might actually be MORE room because the grab-bar in front of you was removed to allow the new lapbar to rise up fully when unlocked.
-Rob