BasicX-24 (http://www.basicx.com/): 32K memory, requires 20mA plus up to 40mA I/O loads, operates at -40C to +85C. Programmed in BASIC (ugh) via serial cable.
Arduino (http://arduino.cc): 16K memory, requires 50mA plus 40mA per I/O load, operates at -40C to +125C (estimate based on range its optional temperature sensor functions at). Programmed in a C subset via USB port.
So we end up with a classic rocket science trade-off. There's an easier to use, robust kit-- the Arduino. And a more bare-metal rig-- the BasicX-- that has better power usage but is a bit harder to hook up. Both are flyable. So do I go for ease of use, or performance?
I'll clearly go for performance. The lower power requirements of the BasicX are an overwhelming plus. As a computer scientist, I'm not worried about the ground issues-- hooking it up, programming it, testing. This is a first launch, and I need to ensure everything is as 'tight' as can be.
However, were I to launch a second (wooden?) satellite, I''d be tempted to try the Arduino, just as fan service to the DIY community.