Dudelsack -
I have a tandem trike:
It's called Big Red and built by Greenspeed.
I thought I could get my wife out for some exercise. She has osteoporosis (a fall would be horrible) and weak legs. She rides with me occasionally for short distances but is not really into it.
Instead I ride with guest stokers when I can find them. This past Sunday, Karen (of the FANY Ride) and I did the 44.4 mile loop around Lake Keuka at the Great Finger Lakes Bike Tour. Sometimes I take it out solo. Altogether it probably gets a 100 or so miles per year, so just a few percent of my total.
The advantage of a trike compared to a 2 wheeled recumbent: very stable. The tandem is even more so. You can roll a trike if you take a corner too fast. The tandem is so heavy, I think it would just slide (but I haven't tried the experiment!).
The disadvantage: every pot hole gets three tries at you!
- Ed