Nothing is 100% compatible, especially if you replace an 8-bit core with a 32-bit core from another brand. But in this case, with a very little job you can use virtually all the Arduino’s libraries to get more powerful devices. This means the phrase “First 32bit Arduino-Compatible”
We know very well LeafLabs Maple, but that’s another thing.
Note that – like you – we have no interest in Microchip, Digilent or Arduino.

It is not “First 32bit Arduino-Compatible”. It may be the “First 32bit Arduino-Compatible available from Digilent”, but I think that is extremely misleading.

If one makes the effort to check the “First …” claim, at say Wikipedia:
http://en.wikipedia.org/wiki/Arduino
There are a bunch of 32-bit Arduino compatibles. I have owned a LeafLabs Maple, for about a year. It implements the Arduino libraries on a fork of the Arduino IDE, uses the same gcc under the covers. I think LeafLabs Maple was available in 2009, but you’d have to do some checking to confirm that.

Further, there is an analysis of incompatibilities on the web at
http://ruggedcircuits.com/blog/2011/05/22/microchip-chipkit-and-arduino-pin-compatibility-analysis/

Like most 32-bit processors, it runs at 3.3V, and not 5V like an Arduino.
Not at all surprisingly, some functionality on pins is different to an Arduino. I have no problem with that. I wouldn’t want them to spend a pile of cash trying to exactly replicate an ATmega.

The analysis at ruggedcircuits.com also notes that some of the Arduino language hasn’t been ported, but that is just software, so I’d expect that to get done at some stage.

Please remove the “First” from the title, and note that it isn’t fully hardware compatible, and the article is fine.

I am not a member of LeafLabs staff, and have no financial interest in LeafLabs.