Mudamaker,
I don't see why metric units have anything to do with the machine. Can you explain please? Are you thinking of the chuck? Most machines here had 1/2" shafts on the bits.
I see no problem with an all-metal machine. Maybe even better, as wooden parts will wear out faster with all the flexing and torque. That's one of the benefits of the Millers Falls and Boss.
A wooden base would be preferable, though, for warmth and comfort on the bum...