Having just watched the video about the metronome app, I was confused by the Speed Upper. It appeared to be a steady increase in tempo - the time between each beat was progressively shortened to get to the final tempo from the first tempo. I would think that a more appropriate (but perhaps harder method to implement) way of increasing the tempo would be do to it on measure boundaries. If I want to practice a difficult routine that is, say, 3 measures long, I would want to do those three measures at the start tempo, then have the metronome increase the tempo for the next time through the 3 measures, etc..
If I wanted to get really fancy (actually, if I were to ask you to get really fancy), I would offer the ability to repeat those 3 measures a specific number of times before increasing the tempo to the next interval.
And, really, really fancy would be to increase the tempo at some non-uniform and random amount (2 BPM this time, 10 BPM next time) and perhaps, sometimes decrease the tempo before stepping up again.
I'm an Android user - I've seen you say that you aren't making updates to that version until it pays for itself - so I'm not holding out hope that I'll see it any time soon. But, perhaps you could work out the kinks on the Apple version and I might see the benefits a little sooner on Android?
Anyway - really neat app - keep up the good work. And, BTW - cool hat in the video!