I think I need to add a line or two regarding porting to other processors.
Cosa is right now very much adapted/optimized for 8/16-bit MPUs with very limited memory (SRAM). Moving to something with 8 Kbyte SRAM or larger I would redesign the core towards a true micro RTOS with threads, semphore, message queues, the works :). There is no way to scale upwards without that. The device driver layer would be rewritten. And the programming model moved towards active objects (actors).
Cheers!