It all depends on you really. I get guys who have never flown a small light twin let alone a piston driven aircraft and they have done fine with the 2 day program. Then again I have had a good number of people do the 10 hour program and 15 hour program. The numbers are kind of misleading. You get 8.5/13.5 hours of training and the use of the aircraft for the checkride. But you don't want to go into a checkride wishing you had done the 10 hour program instead of the 2 day. You could even find someone who may rent a small twin and go up for an hour or so and see how you feel in it.