I can’t understand why you would need to send your entire project file to anyone except when you want them to mix/master your music in your absence. Since you write music for picture, you obviously have a video file with basic sound (dialogues, etc.) as a reference, which in turn normally has a beep sound 2-3 seconds before the picture starts. That is obviously the sync reference for everyone working on that picture. I always include that beep in the rendered/bounced music wave file of the entire reel when I send my music to the sound editing/mixing studio, be it just a demo mix or the final master, and everything will be just fine. Maybe you work differently or I’m misunderstanding the whole point in your post, and you’d think why is this guy stating the obvious while he doesn’t even understand what I’m talking about…
Getting back to the ProTools MIDI subject, in addition to the fact that the MIDI capabilities of Cubendo are superior as stated by other friends in this post, I would like to warn you against switching to ProTools as a currently Cubendo user, simply because they are two totally different apps in terms of architecture and UI, and for you to learn ProTools, you will need to entirely rewire your brain. IMHO, there is absolutely no reason for a Cubendo user who writes music for picture to switch to ProTools.
Cheers