My only concern is its speed. At 20 Mhz it will be hard to get decent transfer rates.
I believe this chip is a 6 clocker, thus = 40MHz for a 12 clocker.
If speed is your concern, you need look at SILabs where you can find a 100MHz 1 clocker = 1200 MHz for a 12 clocker. I hope you are aware that for the '51 "clocks per cycle" is as much - if not more - important than frequency. i.e. a LPC running at 2 MHz is as fast as a regular '51 at 12MHz.

Erik