If you do not care about debugging then use VBCC.
Matt can give you more detailed infos
/me casts Summon Matt Hey
Matt Hey suddenly appears in a puff of mystical smoke 
That mystical smoke really lingers

. I think this is more your territory anyway. SAS/C is the fastest and one of the best development environment for a low end Amiga. He should not use any of the funky SAS/C functions to maintain portability and should test with VBCC from time to time to make sure his program compiles with both. VBCC is portable, easy to install, currently supported and free so it's the logical choice for portability. It is bigger, slower and does not have a debugger made for it as compared to SAS/C. Here's the link to VBCC...
http://sun.hasenbraten.de/vbcc/