Can you please share with us how you managed to use SDCC with CC2541 and TI's  .r51 files? I use printf for debugging anyways, so I just need to create hex files.

BTW, I use cc-tool in Linux to flash with success:
The project is here (http://sourceforge.net/projects/cctool/files/) but I had to make some small fix for it to work in my Fedora19, the mirror is here (https://github.com/dashesy/cc-tool)

Maybe with some effort and combining with (http://ccdebug.sourceforge.net/) on-target debugging can be feasible too.

Thanks for any pointers