I'm looking to upgrade to full frame so am considering the 6D. Is the low flash sync likely to give me problems in the future? I shoot some portraits (of dogs mainly) using speedlights and can't see that it would affect how I work currently. Thanks.
The 6d is a nice alternative to the 5d3 if you are looking for a new camera. The 5d2 is still a fantastic camera as well.
The sync speed won’t be an issue for you unless you are dealing with over powering bright ambient light sources. If that isn’t something you deal with much then don’t worry about.