I can attest to SheFly's amazing ability to do the TT on a tandem with her DH. I have seen it!
I just don't want to have to take direction from my DH; I think we would actually work well together, after an initial period of arguing. I've noticed that our riding has become more and more in synch as the years go on. We almost always shift at the same time, though we may be going at slightly different speeds. But, the whole thought of a tandem scares me a bit.
A couple of years ago we went on a weekend trip to NH with our club. The leaders were on a tandem. I'll never forget as they passed me going down a hill, and the woman on the back was taking photos of me riding. They were the only people I passed going up the climbs in the White Mountains, save for 2 very slow and new riders .