Thanks everyone for your comments. I really appreciate it. Trying both is indeed probably the practical solution. But I confess I find all this a bit intimidating and was hoping there might be a decisive choice between one or the other. I guess it would be possible to install both, wouldn't it? If Hypercard is fat binary, I suppose it might run at the same speed under either emulator?
A lot of us will be very grateful to hear your results. And yes, you can certainly install both. I have both installed on my Mac. They don't conflict in any way.