We did the name change via our I-751 as well and it worked out fine. We also did not change her name on the marriage cert so it's ok. It sounds like SS and DMV vary from state to state because we were not permitted to change the name on SS until they had some documentation from USCIS that the name had been changed in their system first. They did finally agree to change both once we brought in the first NOA and biometrics appt forms which showed the new married name.
We did attach a cover letter requesting the name change as well. Not sure if it's necessary, but it's what we did and it all worked out well.
jross got a reaction from Eve&Josh in Changing your last name when applying for ROC