hmm wondering does the 50-200 have SWD. From what I have seen from E-M1 focus sample tests with four third lens, lens with SWD perform alot better than ones that do not have SWD.
The 50-200 was updated with SWD focusing motors in 2007. I originally bought one of the pre-SWD models just after the SWD model shipped in October 2007, after trying both on the L1. There was little difference in the focusing speed on that camera, and the pre-SWD model felt more balanced to me (never mind I got it for just shy of $900 new where the SWD model was at least $1150 at the time).
Never had any problem with focusing speed or accuracy on the E-1 and E-5 when I acquired them. The E-5 drove it a bit more swiftly. I once tested it against the SWD model on the E-5 and that indeed focused a bit faster, but the difference was still small to my perception.
I sold that one in late 2009 as I found I wasn't using it much ... the ZD 50 Macro combined with the EC14 teleconverter was a better tool for my use then as it was much smaller, lighter, and convenient to handle. (I almost always used a sturdy tripod when I'm using the 50-200 ...)
Scroll forward to the E-M1 introduction ... When I first handled an E-M1 at the store, the Olympus Rep had a 50-200 SWD there for us to try, and one of the other folks there to see the E-M1 brought his pre-SWD 50-200. For reasons I cannot explain, the pre-SWD model seemed to focus more swiftly on the E-M1 to me. I've since read reports from users on the various photo forums claiming both ways ... that the pre-SWD model is the one to have for the E-M1, and that the SWD model is the one to have.
When I looked for one to reacquire, I noticed that pre-SWD models were generally priced $300-400 less than the SWD models. That clinched it for me: I bought this one in near mint condition for $550. It focuses very swiftly on the E-M1 (far as I can tell, as fast as it did on the E-5 and more accurately) and also works as nicely as my original one did on the E-1. Good enough for me. I focus this kind of lens manually about half to three-quarters of the time anyway...
The other thing that I've heard is that the SWD model was lightly refreshed optically and vignettes less at the longest focal length settings wide open. I don't know how true this is.
(The ZD 14-35/2 SWD ... now I've heard consistently that that one on the E-M1 autofocuses MUCH more consistently, swiftly, and accurately than it does on the E-5 or any other FourThirds body. Not that I'm in the market for it, but it is without a doubt optically one of the "Super Lenses" of the recent era. But small and light it is not.)
G