Just now I'm working on the evaluation of 8051 derivate for my new project.

Main requirement are:
- 2 x UART,
- at least 8kB flash memory (ISP)
- at least 1kB SRAM and
- PLCC pin assignment preferred.

Into narrow selection it comes:
- Dallas Maxim DS89C420 and
- Philips P89C669.

From my local distributor I've heard that Dallas Maxim has some internal problem with DS89C420. DS89C420 is also more expensive and it has less flash and SRAM.
In another hand I've found in P89C669 errata sheet some problems with 9 bit UART communication (and I need 9 bit communication for m-bus protocol). And here is also unpleasant possibility to erase the boot vector.

What would be your selection according to my evaluation requirement?
With which derivate do you have good experience?
According to your experience, what must I be careful about these two controllers?

I would be very grateful for all yours suggestion.

Best regards,
Damjan