I never did a Dynasty in Sims 3 because I never got skilled at... skilling (lol) enough to manage the challenge. It's no easier in TS4 (not for me, anyway), but I've spent more time learning the ropes so far (more play time, honestly, because I like TS4 more than TS3) so I'm so going to be in on this. I, for one, can't wait to have that rule set out!
Hopefully all the bugs that might make it difficult will be fixed by then!