Can you work with EX files in Avid yet?

Yes, I'm doing it in Avid Media Composer 2.7.2 on a PC.

There is only support for the formats that is the old XDCAM HD formats like:
SP 1080i50 (1440x1080)

You have to use the Sony Clip Browser and export to .mxf files that can be imported into Avid.

I made this thread before on how to get 1080p25 files into Avid using ffmpeg.

http://www.dvinfo.net/conf/showthread.php?t=108923

More tips on ffmpeg and EX1 at ex.bolanski.com

Does this give you full support for the EX codec? No loss or problems?
What formats can you not get?

I tried http://www.ex.bolanski.com and didn't get anything .

I have a major client who uses Avid so this question radically affects whether I buy the camera yet.

It's not www.ex.bolanski.com its ex.bolanski.com.

Avid only supports SP formats to my knowledge, as stated in my post. I'm in a PAL area so I use SP 1080i50 I guess 1080i60 would work to but I don't know.

I also have a solution to use HQ 1080i50 and HQ 1080p25 but I don't know how lossy that would be, my guess is not much but try for yourself and see.

Go to ex.bolanski.com and download a clip if you like, I have a zip file of almost every format the camera can do, but they are only 9-12 frame clips. I made them for users to test if there NLE's can use them at all.