Should one go for skinniness and speed, or width, comfort and better puncture protection?
I think that comes down to how much you a) need the comfort or b) don't need the punctures.
If you're touring or leisure riding in good weather, an occasional puncture isn't a big deal (especially on the side wheels of a trike, where you don't even have to faff about taking the wheel off to change a tube). But when it's cold and miserable, or you're on a time limit, it's worth having something a bit sturdier.
Note that it's never a simple case of thinner tyres going faster, but especially not when they're lightly loaded as they are on a Trice - a wider tyre may have less rolling resistance, and you probably want to keep that to a minimum.
Oh, and a nice grippy compound on a tadpole trike makes for awesome fun on the descents.