Tough decision. I completely understand your situation. So much, that I just went out and added to my own stable. I have two 'dubs, and they're both just a lot of fun to ride. However, two TW200's for one guy is one too many. My son has taken one of them out occasionally but he'd have as much or more fun on a YZ85. He's young, likes to go much faster than a TW allows, and doesn't pay for his own doctor. Privilege of youth.
I love bombing around on my '06 but I recently starting wishing I had just a little more power. I spent some time looking around and had a few different bikes lined up to check out, and then my new bike appeared yesterday on the local Craigslist. Over my budget, but calling my name. "Snoopaloop," she called to me. "I am yours. Come and take me." I loaded the ramp in the truck and high-tailed it to her location. Haggled, bargained, and cajoled until my name was on her title. She's a little bit fugly, kind of like my TW, but she's all mine.
Point is, I can see getting rid of one TW, but I think I'll hold on to the second. I took the Duc out for a spin and she is just an absolute rush. BUT, I anticipate days where a mild-mannered little 200 could be just the ticket for a casual cruise, or a quick spin through the woods. For the money, you just can't beat a TW as a fun alternative, especially if you can afford two bikes.
If you could find a good deal on a TW, why not keep the 1200? You know you'll look back in 5 years and ask the same question that you're asking right now about the TW. You called it your "sweet sweet bike" (observe the two "sweets" relative to the single "sweet" you called the TW). The only rational decision is two bikes.