I use RDX for my unit frames, it allows any order you want, alpha, reverse, class, class/alpha, specific class, etc etc etc... if you can dream it, it can sort it.

You can even simply arbitrarily order the group by using a nominative set... the learning curve on RDX is not small so be ready to tackle something that isn't easy if you try it out. On that same note, you can use RDX to replace nearly every element of your UI, thus eliminating dependency on many small UI mods that break patch after patch.