[aroden]

Back problems lead me to a recumbent like your talking about. Love my Aero. Doesn't have the fancy gearing but I'm ~20-30% faster and with no pain (except for hills). Still expensive but comparable to traditional carbon bikes similarly equipped (about $3-4k). Cruises comfortably at 25-30mph; good downhill speeds get into 50-60mph.

http://www.bacchettabikes.com/bikes/performance/carbon-aero-...

[blacksmith_tb]

Bacchetta make an aluminum version for $2K. I haven't ridden many 'bents, but I would have thought under-seat steering would be more aero, and possibly more stable at high speeds (can't imagine descending at > 50mph on a diamond frame, don't think I've ever gone faster than 45 or so, and that was nervous-making).