Got a response from Atmel today. I asked them about the multimaster issue with TWI/I2C and the ATMEGA series. They said that the XMEGA series corrected this issue and should work fine.
I don't think any of them come in dip packages. (that concerns me for OSCAR modules and ease of use)
I don't see any major differences with them. The only benefit I see is the ability to not have to use the software work around for multimaster modules.
Does anyone have experience with these chips?
I'm toying with using them for my OSCAR modules and don't know if its a good idea or not.