Will a slower accelerator provide better compatibility for old games? It sounds like you are suggesting that is the case.
No. Not if you're comparing a 68030 at 25MHz vs a 68030 at 40MHz, or whatever. Mostly this is in relation to more advanced processors (like 68040 & 68060) which can take a little more configuration work to make some games work with them.
Supposedly there's some games that will run "too fast" with a faster processor, but I've never seen one, personally, and WHDLoad has hooks to compensate for this kind of stuff.
Personally I wish older games would take advantage of faster processors (for example, to run more smoothly), but you have to think back to the era they were coded in, and the fact that most games were coded for the "lowest common denominator" (A500 with 1MB & no fast ram or HD, in most cases). Turrican 2 stutters if you jump in the waterfall area at just the right place with a 68060 as it does with a 68000, haha. :p
