Jeff,
I really can't fit a matching speaker for a couple of reasons. Weight and height are major issues. If I shrink the box down the f3 goes up too high. The original pair of ones have the Motorola piezo tweeters. My early guesstimate is the f3 with the Alpha 6 will be just about 90 HZ. Efficiency will be just about 1DB less. Right now it doesn't look like a bad alternative. Of course Wayne knows best and may shoot it down.
Steve