Well it turns out that I can ride a 'bent bike. In a roughly straight line at least. Turning, not so much. :)
I paid a visit to Just Bents
today and tried out a bike and couple of trikes. The trike felt quite odd - the larger wheels and higher seat make for a very different ride and I did find the grip shifts a bit difficult to manage (I'm more of a bar ends kind of a guy).
I had a shorter ride on another trike with suspension and a hard shell seat. I didn't really test the suspension because the seat was angled far too low for me. I definitely prefer the more upright seats.
I may be going back there soon...