I said fabrication process AND RTL architecture matters more than ARMv7 vs SPARCv8. They are both quite nice RISC architectures. Nothing in either one is especially power hungry.

Sure you have Thumb, that saves a little on memory bandwidth which is good. But nobody uses it anyways, and you might run slower so you can't sleep as fast.

I like the J2 (the open source sh) project as well but it doesn't have a MMU which rules it out for anything but simpler embedded projects.