I've had a Meditor 4000Di Mk.II in my A4000 for almost a year now. I haven't experienced any jerky video using a Sapphire Radeon9250 128MB. My is loaded up with the Radeon, SB128, Ethernet and USB 2.0 and it all works good together. The higher rez screen modes are really nice. Just remember, the Radeon doesn't mode promote, so you will have to find a solution to use native mode for games and such. I use a Dell2420 monitor. The DVI is connected to the Radeon and the VGA is connected to the AMIGA video out with a C= adapter.
If you decide to get one PM me and I will send you a setup guide that will greatly help you as the one elbox provides is pretty bad.
