Speed isn't a consideration for me. I'm not a good enough sewer to go full speed on any of my home machines. Also, I do this for enjoyment, getting done quickly isn't the point. If I was in it for production and/or was able to sew faster then speed would be important to me.
On a home machine you can change the diameter of the motor pulley to a larger size to increase your speed but there will be a loss of torque as a result. It would probably be ok for most fabrics but you would probably have trouble with thicker fabrics like denim. Some of the domestic machines had 1.3 amp motors on them as opposed to the .6 amp motors Singer used. One of these slightly more powerful motors with a larger pulley might be a good combination on a home machine. There doesn't seem to be any middle ground between domestic machines and industrial machines, I would be concerned about trying to hook a domestic machine to an industrial motor. The extra power could easily cause parts breakage in a machine that's not designed for that much power.
I haven't had the opportunity to try an industrial machine. The old clutch motors-the motors themselves, anyway- should be nearly silent when they're running. I don't know if the clutches are noisy. The quietness of the old motors compared to modern universal electric motors is one of the attractions of old wood working machines(my other hobby).
Rodney