I can see there may be a historical reason for the delta times, but is there still a "good reason" to keep them in favour over realtime?
In my sequencer "not exactly midi" i just do function below to recalculate bpm to any?

It seem the deltatimes and odd bit format make the files alot harder to read/readout.

function reCalcNotesTime(BPM){
percBPM=OLDBPM/BPM;
for (var i=1;i<maxtrack;i++){
for (var j=0;j< track.midiMess.length;j++){
if (track.midiMess[j].time!=0){
track.midiMess[j].time=track.midiMess[j].time*percBPM;
}
}
}
}