I've got a XAT650M and I see that there's a very similar looking XAT600SM now:
What makes it confusing is that the model number on the box mine came in is HS1177M, but the model number mentioned in the product page above is also HS1177M.
The only difference I've noticed is that the component layout on the rear board is different.
So what are the differences between these 2 cameras? If there's been an update to reduce spurious emissions on GPS or UHF-RC frequencies, I'd like to know.