As the sales manager for a recumbent bike manufacturer, I can tell you a few things. Taking the pressure off your sitty bones (the ischeal tuberosities) is amazing. Having a seat back to press against adds leverage to your pedal stroke. Sitting upright greatly benefits the spine and shoulders. But aerodynamics without shells or screens piles up as you go faster. Most folks don't like hill climbing on a 'bent. And the control that comes from having your hips over the cranks is not inconsequential. I've ridden 'bents into mtb-style challenges like traversing large culverts; as long as you can carry momentum, you're good. I own a LWB 20"/26" and would like a tadpole trike, once the tech gets another weight drop. And I've got a quarter of a million commuter miles on a beach bomber with a layback seatpost and bomber-thick city slicks (the ones with the flames on the sidewall). I run the tires cuz I almost never get a flat with them. I run the layback cruiser bike cuz I get so much control out of my hips and "flat foot technology" is no BS. The recumbent is like a weekend party excursion, though- ergo, comfy, laid back, efficient.