Panasonic 100-300 or Olympus 75-300 (m4/3) Please Help!!!

Bangers and Mash wrote:

I’m still trying to figure out my options for bird photography. I was thinking along the lines of saving for a completely different system altogether than the E-P3 that I presently own, but when you factor in the costs involved I have to stay with what I have. So my question to you folks is; Will the Panasonic 100-300mm lens work well with my E-P3, and is the IQ worth it? Are there any issues with focusing etc that I should be aware of? I could go with the Oly 75-300mm m4/3 lens, but it's $400 more than the Panasonic. Can anyone please advise me as to which would be the better choice and particularly if the Panasonic lens will work ok on the E-P3 body?

One thing I just found out is that the Panasonic lens required a firmware update. I’m wondering if that is the case . . . how would I be able to update it’s firmware while on an Olympus camera? Would that be possible?

Thanks guys.