This is not a 1.00g topic. Shoo! We have a perfectly good article about the differences, and you can play the 1.00 MP levels in 1.23 nowadays anyway.
I don't see any harm in answering this question; yes, it has. blur arose from the dead and edited some code that nobody else understood and now that particular crash is gone. (Or so I've been told, since I wasn't personally able to trigger it to begin with.)
My position on Tweedle is that someone should just code him/them up in AngelScript. If they do a good enough job, maybe it could be converted into JJ2+ code, but in the meantime there's nothing preventing people from writing their own Tweedle behaviors just as with any other sprite set.