Kendra Little explains why enabling row versioning adds 14 bytes per row:
I love it when someone sends me a repro script, but in this case I didn’t need to run it. The first thing I did was to look at the two numbers given for row size, and to subtract the smaller one from the larger one: 724 – 710 = 14 bytes of difference.
That bit of information alone gave me an immediate guess of what was going on.
Click through for the solution as well as a more detailed explanation of one of the trickier scenarios.