Those back lit keys are definitely the cats meow.I have a Pro43 and would guess the 125 has better audio (why I got my Pro97) so others can hear in a group setting.
Alpha tags are nice especially when a "guest" is listening. Display visibility especially needing a light the Pro43 is weak but surprisingly the 125 does not have backlit keys like Pro97 and that would eliminate it from my roster. The near field searching is a great feature the 43 does not have. One more beep of the Pro 97 horn: 1000 channels.