I wonder which RCM are the most common, since I want to create some small sample programs for Rabbit development using SDCC and OpenRabbit.
This is something that you should talk to Digi Sales about. They can answer your questions or obtain the answers for you.
Recommended for new development is the RCM6000 products like the RCM6700, this uses Dynamic C 10.72E which is the latest running software for this product.
On the other hand, SDCC currently only supports Rabbit 2000 and Rabbit 3000, so I’ll start with RCMs for those.
Of course, one could still use a Rabbit 4000 / 5000 / 6000 in Rabbit 3000 mode.