Are you speeding your clips with the Time remap tool? I thought 200% was the maximum you could speed something up anyway. I use the Time remap tool to speed clips up and its nice and smooth providing I shot it nice and smooth.
I used the time remap up to 10,000% on a clip for a minidoc I did while in Kauai... basically a time lapse... turned over an hour of footage into 36 seconds.... I was AMAZED at how beautiful it came out. Smooth as could be.
It's 88MB and can be downloaded here to see the effect... it's the fist 30 seconds or so of the vid
I like it, especially when you cosider that it was done in 24 hours start to finish including writing / audio composition / special effects / editing / voice over / the whole shebang... other than shooting the footage which was done over a two week period (really only about 4 days of shooting and it was all just run and gun, no tripod, no accessories, just the camera and a UV filter)
Its also my first project with the DVX, I just recently graduated from using (it's embarrasing to admit, but a Sony PC100 and uh ummm... Microsoft Movie Maker)
And, that is the whole thing... for now. I did it for the "contest" at Marty Martins website (http://www.imagenfilms.com) and the limit was 5 minutest... the project is 4:59:15 with the credits
I have several more hours of footage that I will EVENTUALLY create an extended version with.