Alpha with TT15 is awesome! It's revolutionized my hunting and greatly added to my peace of mind. Just recently a guide/trainer suggested the mini for smaller dogs. He claimed he never noticed a range or battery life issue. Had I talked to him before buying a regular tt15 for my new dog, I might have bought the mini. I flirted briefly with the idea of selling my new TT15 and buying a mini, but decided against it. Cinched down to my preferred tightness, I think I have only one more "hole" available on the strap. For reference, the new dog is a vizsla of about 33#.
Not sure I would run two dogs without it.