I went through with just radiation and a unilateral modified neck dissection, even though the chemo doc wanted, after the radiation and surgery, (6 years ago it wasn't done concurrently) to give me a chemo wash to be sure any micro mets were dealt with. I was so beat up after 72cgy of radiation (not IMRT) that I opted out. I just couldn't do it, and I was so sick from the radiation I just wanted to quit. Turns out 6+ years later I was lucky, and I am still on this side of the grass and in pretty good health.
Having said that, we have members here on the board who have posted about not doing the chemo, and they are now fighting for their lives. This is a tough call. I have an opinion, but I do not want to sway you one way or another. This is a very important personal decision that you and your docs or additional doctors need to make together.
The docs may be very correct in their assumptions. Just remember these are very informed OPINIONS, and not any guarantee that they are right. Whatever decision you make, base it on the opinions of the best doctors you can talk to. Once you make your decision, don't look back and second guess yourself. You could have your records sent to another institution and pay for an evaluation without having to travel extensively to get these extra ideas and opinions. Whatever you decide, you know we'll all be here to support you.