I've also thought about this some years ago:
http://midi-clorianos.blogspot.com/2010/08/electronic-music-stands.html

It is probably not going to be a very successful commercial product, in a world on making music is similar to fast food: cheap and quick, using garage-band and auto-tune so every idiot may create popular music on his comfortable dorm. But I think that the true way will be the hard work way again in the future, learning to read music sheet and years of constant practicing, like in star trek.

Regards,
Pedro

I think the MUSESCORE software may be a help. You can download a version of this for free.

It is designed - according to the web docs - to help learn to play music, and allows the loading and playing of a midi file, while playing along with the midi, and seeing the score on the screen.

You might at least look at the web site and see if this might help.

Geoff

Thank you!
I know and use already Musescore to write my music. I think from the v.2 has became really really good to write music scores and MIDI as well.

Musescore and the Musescore Score Book have also all the playback features that I would look for, but in a really un-accessible in the situation of practicing music with an instrument.
(I mean: changing loop starting and ending point, speed of execution, mixer of the parts schould be at one-click-distance, specially in the mobile app).