You are looking to trade the wrong bike. Trade in the Bonnie for the Thunderbird. Keep the BMW.
I wish I could have all three, but then I'd have to get rid of the wife. Hmmm. I love the Bonnie. Got home from work and first thing I did was get on the Bonnie for a quick loop around town. I do enjoy reading all the comments. It does appear that everyone appreciates that the BMW is a really nice bike. You wouldn't hear that on all forums. Some forums only like the bikes that they ride and can't appreciate other makes and models.
I can tell you that on last weekend's ride into the mountains it was nice to have the windshield down on the twisties and then electrically up it went on the highway. The RT is a very comfortable bike and I probably have the best of both worlds with the RT and the T100. But the T Bird is a beautiful bike.