The system you have produced with MidiNotate Composer is a fascinating one, and, although with less rhythmic subtelty than Sibelius 4 (try writing septuplets using MidiNotate!), it is a useful, if basic tool. My overall impressions are favourable, therefore, but I would ask you to consider two further improvements:

1) the ability for the programme to offer an "atonal" key setting, so that one doesn't have continuously to rewrite notes using the enharmonic spelling option - very frustrating to have to keep changing those C#s into a Dbs all the time!

2) the ability to write 5, 6, 7 etc -tuplets when one wishes to: contemporary "serious music" composers do use more than just triplets in their music, and as a professional composer, I find it quite irritating not being able to do this on a programme that is generally rather a good one.

3) the ability to write a piece of music so that the parts are in different keys (and even time signatures) at the same time. This isn't a new thing - Bartok was doing that back in the 1920s and 30s. So come on - let's have that option too.

4) the ability to have a template facility to put written tempi (and especially metronome markings!) in pieces we write. Sibelius does this as a matter of course, and it is a helpful facility.

So, overall, MidiNotate Composer is not bad. But I won't be disposing of my Sibelius 4 just yet, but then neither shall I be prevented from writing music using MidiNotate Composer. Let's call it 7/10.