... provided it doesn't get eaten by battery acid. :-(
the A3640 as previously stated was basicly a botch job to bolt a 68040 chip onto the A4000's cpu slot. built cheaply and designed quickly. comparison to any other 040 board isn't really fair.
personally, i'd rather have an A4000 with A3640 than an A1200 with an apollo. day to day stuff you aren't going to notice the difference, and you have the chance of better upgrades anyway... :-)