New 50-200 SWD or old 50-200

I've got my flash picked out. Now my next dilemma.

I am going to purchase an olympus 50-200 lens but am not sure to buy the SWD model or get its predecessor.

Is it worth the extra money? Has anyone bought the new lens and have done any comparisons?

I think the SWD lenses offer faster focus when used with the improved E3 focusing system. Even though the SWD lens will work on a 510 I am unsure how much faster it will be than the older lenses. The street price on the new one is $1200.00 while the older one is around $800.00 or a little higher. You might even pick up a used one cheaper. If it were me I would go for the older version unless you are looking to get an E3 soon I would go for the newer version. You could use the extra $400.00 and get the 1.4 tele converter.
Also being 2.8/3.5 for the SWD you won't be gaining any speed with the shutter by going with it.