Dan I have a twin with counter rotating props and a twin with regular motor. The only difference is on take off you don't have that tork pull and in a big loop it is easer to keep the wing level with counter rotating motors.
A tail dragger twin would be happer with counter rotating motors. But either way it is not that big of a deal. If I was going to build a big Misquetio over 100 WS I would try to go with Counter rotating motors. The bigger prop the more tork.