I love the aluminum wheel/10" setup, even in the '48 which met all known criteria for NOT using a light wheel...
Engine revved like an electric motor. I would assume car accel was helped a bit, too, but since I changed all sorts of things at that time I didn't get any way to gauge that. Only noticeable downside was a very slight need for more revs when starting from a dead stop. Flatheads have enough low end torque that this was barely noticeable, nothing like driving a furrin car or anything.
Also, pretty soon after that swap, my left leg shrank to the same size as the right one.