2 part waterborne epoxy vs poly??

I just bought a house with wood floors. I've gotten quotes from two refinishers. One uses polyurethane & the other uses 2 part waterborne epoxy. The epoxy quote claims 500 times better for long term use, low scuffing & can do it in one day. He also claims that he will not offer a guarantee on the floor if I don't agree to take it all the way down to the bare wood. He says if you just do a minimal sanding & then apply the finish, you will get bubbling and peeling as there may be soap residue or other products left on the floor. Of course the epoxy quote is quite a bit more expensive. He offers 3 coats and the poly quote offers 2.

I'm also concerned that a light sanding will not remove the orangeish/yellow tint the floor now has (1950's floor - probably original shellac on there!) and want to know which one will yellow with time - epoxy or poly?

Any thoughts?

Tks.

MPG