My husband and I are using four-thirds cameras (E-3 and E-520) -- with an OM-D in our immediate future. For bird photography, I'd been planning an upgrade to the 50-200mm (with EC). I'm currently using a 70-300mm. I was ready to put in an order, but I've been reading about questionable AF performance of the 50-200 on MF bodies. Has this been a significant factor for those of you using this combination? I don't want to make a lateral move in terms of lens quality, and would also like a lens that has some responsiveness on my new m4/3 body. The obvious benefit of the 50-200mm (beyond quality) would be the versatility between the four-thirds and micro-four-thirds camera bodies. Do you think the AF issues would be significant enough to make this a poor choice for use with the OM-D? Thanks very much for any help and insight.