Afraid I know exactly how you feel. When I got my FJR, I kept my Vulcan. But anytime I had the chance to ride, the new bike got the attention. After about a month, I felt guilty, and took the old girl out for a spin.
For some reason, it just did not feel right any more. I actualy said to someone it felt like going from riding a ten speed to trying to go back to riding a Big Wheel. It just didn't seem to fit right anymore.
I could not stand to see the bike neglected, so I placed an ad in the paper and she got sold in about a week.
I do love my FJR. And at times I do miss my Vulcan....but luckily I'm not done with the old twin yet. I picked up a fellow VN owners "old" bike when they bought a "newer" Vulcan model. I got it to make it into a solo seat custom, but money and time got put on hold.
Hopefully after my house gets built and my shop gets back in shape, I'll have the time to finish the project. In the meantime, I still have my FJR...and the two of us are still very happy.