It seems to me that affordability is the only thing really lacking now. I don't know what specific programs you need, but I haven't had any problems with compatibility. And for the most part, it seems most software from Apple gets high marks in efficiency.
I've got boatloads of problems with software compatibility.
Files created on the G3 aren't recognized by the imac G5.
All my pagemaker 6.5 files made on the G3 are tossed aside by the G5 as not recognized. So I've essentially lost thousands of Pagemaker files and need to go to the G3 to work with pagemaker. Arrrgghhh! Plus I can't launch the OS9 emulator as a start-up on the G5.
After many days and many choice words, I was finally able to figure out a work-around for the G5 to recognize the old WriteNow files. Now I have the joy of opening thousands of WriteNow files on the G3, converting to RTF and saving so the G5 Text Edit can open them.
Switching from the G5 to the intel-based model I hope will be less troublesome.