The cost of the 20M2 [RB-Pic-31] wasn't that much more than the 08M2 and is less than the other PICAXE microcontrollers such as the 18M2 [RB-Pic-32] (other microcontrollers with less usable pins!). The 20M2 offers 16 configurable input/output pins and harnesses new technology including: internal temperature sensor, Manchester radio encoding by use of simple commands [rfout, rfin], additional memory, time-sliced parallel multi-tasking of up to 8 tasks, etc. I use the 20M2 in my sensor pack wireless transmitters around the house with the 830 Tie Point Interlocking Solderless Breadboard [RB-Cix-10] and the SeeedStudio Adjustable Breadboard Power Supply [RB-See-93]. Highly recommended!!