First of all, thank you all for this great piece of software!
I'm using hydrogen in connection with jackd and I run into two bugs when using the bpm change table:
1) when using jack transport (e.g. in qjackctl) to set the song position, the bpm is not adjusted correctly. It simply stays where it was before the positioning. Manual positioning inside hydrogen (by clicking on the time line) sets the bpm correctly.
2) once the song ran over a bpm change and I reset the song position to start, the first beat is played double and the hydrogen timeline is out of sync with the jack timeline.
Since I'm a software developer myself and I'd like get a fix as soon as possible, I'd be happy to help out and do some more debugging. I could use some instructions on where to look, though.