Anybody using the Canon 300mm f/2.8 II with the 2x III as routine combo?

I have read many reviews, including Artie's, of the new Canon 300/2.8 L Is II lens. Roger has provided some excellent information on what the lens should be capable of. But I'd like to hear from folks who have purchased the new lens and are now using it with the 1.4x III and 2x III as there everyday lens on a 1DMk4 or 7D for bird photography. I am currently shooting with the Canon 400/4 DO +1.4x and wondering whether I would get much higher IQ, consistently, and in a variety of lighting situations, with the new 300/2.8 II + 2x III combo. These are my only two options because of physical limitations. If there are folks who have had great success with the old 300/2.8 +2x I'd love to here from them. Thank you!

Glen Fox

I am using the 300 2.8 II with 2x III and 1.4x III. IQ with both the TC's is fantastic, I'm very happy with that. However AF speed is disappointing, at least with my 7D. BIF is only possible if you prefocus and the bird is against a uncluttered bg
The 300 2.8 when used wide open without any TCs gave me such wonderful results that I was very reluctant to ever stick on a TC again, thats the reason I got the new 600 f4 II

Thank you for this information Aditya. It all sounds positive to me as I have no intention of using the lens for BIF with the 2x, or even the 1.4x. It will be used mostly with the 2x for bird "portraits". In most cases one has an opportunity to prefocus. I look forward to hearing of others experiences with this lens combo. Glen

Currently I am considering buying 300 is II and was worrying that it may be too slow for BIF (with tc III)
I also niticed my 70-200 f.8 is II was much much slower in terms of AF when connected to 1.4 II TC.
My question is: have you guys ever compared your gear (300 +tc) with Nikon's equivalent. My friend owns Nikon's 300 2.8 and uses it both on d700 and d3s together with new nikon 1.4 TC for shooting football and claims he sees no difference between TC on and off in terms of focusing speed. He also said that he has never seen a person shooting canon lens with TC during matches while you see a lot of 300 + TC from Nikon stable.
Is it possible that Nikon is better in this aspect? Thanks.

I have had the 300mm f2 is 11 for a few months now and only shoot birds. It doesn't replace the 500mm f4 is for sure. It is an amazing lens.
I cannot help much with the 2.0x. I use it with the 1.4 11 only. I have a LOT of pics with it at www.flickr.com/photos/avianphotos
The exif are intact and you can judge for yourself. I am heading to thailand next month for the annual raptor watch at chumpon. And will pick up a 2.0x there for BIF.
I am hoping with an open sky and big birds it will do ok. Check my site between Sep., Oct. and Nov. I will that ironed out for sure.
I am not a good BIF guy. I usually shoot birds on a perch. But I do know with the 1.4 11. It is a very good BIF lens. I have used it for that in Thailand some.

I will also put a detailed description on my blog at my web site. www.birdsthatfart.com
Good luck, Gary