Dang I hate having to deal with dual voltages. Whatever happened to the days when everything was 5v?
It's not practical to do a full emulation by turning the buffers around so I'm going for a "Chip tester". This will allow you to play with a new chip, say a port expander with an SPI interface, by connecting a few wires and "talking" to it with the debugger. This should allow you to generally play with the chip and get the command sequences right in "real time" without having to compile/upload every time.
On another front, due to a monumental stuff up by the LPC designers as far as I can tell ADC4 input and one of the USB connections are on the same pin and cannot be muxed to another. So you either have ADC4 or USB but not both. :0 I need the ADC so it looks like I'll be breaking out the FTDI chip. So much for using the internal USB and saving some hardware.
Schematics nearly done. Looks like a 4-layer board though 
Rob