Dear raino & jono not bono,
Thank you very much for your detailed answers. I got the picture now.
I think I’ll use both methods based on type and needs of the project. Instrument channels seems easier but I am curious how will it feel working with for ex. 50 kontakt instances with 1 instrument 
I suggest you create a Template with only Track Instruments.
You can create thousands (of tracks) of these each with only one instance of Play loaded for each sound.
Just disable them and enable when needed.
In Prefs > Enable Record on Selected Midi Tracks > That way you listen back quicker. To arm thousands of track or switch monitoring on takes forever.
Use folders in folders in folders etc to navigate easy and name them properly.
Good luck !