Well, Wozniak did say Apple demanded that the 65816 in the II GS was clocked at only 2.8 MHz to make sure it didn't threaten the Mac performance and sales..
Although, here he listed purely technical reasons:
http://www.1000bit.it/support/articoli/apple/a2gs/interview_woz.asp Our early ideas for the computer had it running at 8 MHz. Soon we found we had to back off to about 5.5 MHz, and then to 2 MHz for that version of the processor. In the end, the product came out at about 3 MHz, which is a good compromise.
And it's hard to imagine that the 65815 is twice as fast as the 68000, although I suppose that all depends on what you're doing with it...
With the Mac, it was doing everything, so that 7Mhz 68k did feel really slow....
desiv
