Hi, Jodi. I'll try to help. As far a durability, I believe that the oil based will outlast water based. Also, personal opinion is that the oil based will look warmer and more natural. I feel that it is easier to get a better looking repair to a scratch or dent with the oil based.
The big advantages to the water based are that they dry quicker and therefore are usually more attractive to the installers. Being faster drying, they pick up less dust during this time. They are more gentle to the atmosphere and smell better while drying. This is great, but you have to think about the many years that you will have your floor rather than just the finishing period.
I do know that I e-mailed about this same question to a manufacturer of both products and the oil based was strongly recommended. That was what I used and was very pleased with it. For what it's worth, I think your refinisher is leading you in the right direction and I would sure pay attention to what he says.
Good luck and I hope your floor comes out as pretty as you expect. Henry in MI