Hi Claus,

If you're looking for performance, take a look at the Cygnal parts (see links). They make parts with built-in ADC, and can execute instructions each clock as compared to one instruction every 12 clocks (nice eval board too). There are also /6 and /4 clock varieties.

Usually to use a different 8051 family derivative you just include in your source the corresponding header that describes the various SFRs and control bits.

There are a number of compiler vendors that provide downloadable demos with limitations that you probably won't run into for awhile (code size). Check out Keil and Raisonance.

Dennis