Having the front be single wheeled leads to the a lot of instability because turns change your center of gravity. I just bought a recumbent bike and I had to search extensively to find a nice two-wheeler because the 2 front wheel 3-wheelers are quite popular, just like the motorcycle equivalent. Most bikes and motorcycles with three wheels have the same steering linkage you'd find in a car.
Be very careful with two wheel recumbents, I've got half an Ikea's worth of steel bits in my right leg on account of one. The danger is in when your foot slips off the pedal even for a moment and hits the pavement on the downstroke, you'll brake with just that one foot and it is a feed-forward mechanism that you can not break out of. Nasty, to put it mildly. If I had foreseen that particular failure mode I'd have either foregone the bike entirely or I would have placed something underneath the cranks to catch my feet should I ever go there. The lower the bike the higher the risk of this happening.
Thanks for the advice! I've picked up a tall one, and I'm definitely going to keep your story in mind when choosing my clipless pedals to hopefully minimize that risk.
