Thanks, I was talking to the Atmel Tech On Tour folks today and the part I'm really interested in of late is the R21 which has both radio parts and the M0+ in a tiny package.

It has up to 32K of RAM and 256K of flash [2], the larger Cortex chips have the big RAM numbers as you note.

[1] http://design.avnet.com/axiom/atmel-sam-r21-atmel-cortex-m0-...

[2] http://www.atmel.com/Images/Atmel-42223-SAM-R21_Datasheet.pd...