Probably unrelated...
Just chiming in here with a (probably useless) thought:
In regards to the "simplicity" of working out tempo/BPM, it's not always that simple. For a straight 4/4 beat, I'm with the guys here who type in a tempo, and pull up or down if its too slow/fast. However, some of my stuff gets a little more complicated than that. About two years ago I wrote a 10-track "progressive technical jazz-death-metal fusion blah blah blah i dont know what to call it

" album in Guitar Pro. There's a lot of parts that, for example, switch between a 3/4 beat and a 6/8 (triplet-feel) beat. These two things need different tempos to match the click. This is where some math comes into play.
Another example:
Lets say I have a riff, played at 120bpm, 4/4 with straight 8th notes. I then run into a transition where I want to play a riff thats in 6/8, with the same tempo, but the 8th notes are played in a swing/triplet fashion. I have to divide the tempo by 2 (60bpm), and multiply by 3 (180bpm), then at this new tempo I switch to 6/8. This enables me to get to a new tempo (in theory, although when you tap along to it the tempo stays the same - which is the point of the exercise), new time signature, and the transition is as smooth as possible.
During my time writing that album, the examples mentioned above are some of the simpler tempo-related things I had to do. So, calculating tempo isn't always as simple as it seems
