Well, it sorta works. Works better now I've cleared space for the knees. But I've never ridden a real penny so I've no idea how they compare!

Hypothetically, the CoG is probably about the same, as the wheel's CoG is at the axle. Scooting along hanging on the side, it's stable - that's a factor of the height (the period of a pendulum being to the root of its length). I think this is sneaky tallbike / stilt seekrit knowledge, you know: once you're up, it's more stable than it looks.

Steering will be twitchier, I expect, for the reason you give.

I haven't ridden it enough - at all really - to assess it's hole-handling, but it has a fat pneumatic tyre where real pennies have a skinny solid one. We know pneumatics, they're good and they totally took over.

I still want a real one.