This Post being very useful for me, but i didn't came across any situation like mine.
I have a Valid Visa from Previous Employer 'A' till Aug 2017 on my Expired indian passport. I have changed to Employer 'B' with a New End Client and have an Approved i797 notice for Employer 'B' valid until 2019. I also have New Indian passport issued (obviously it doesn't have any h1B stamp on it).
My Question is : Can i travel in feb 2017 for a month on my previous employer valid Visa which is on expired passport?
or do i need to go for H1 Re-stamping on my new passport.