I decided to keep EZdrummer & Co as explained in the solution below 
EZdrummer 2
Big Rock Drums EZX
Classic Rock EZX
Funkmaster EZX
Jazz EZX
Latin Percussion EZX
MIDI packs:
Americana MIDI
Classic Rock Grooves
Fusion Grooves MIDI
Progressive Fusion MIDI
Seventies Prog Grooves
Singer-Songwriter Grooves
Sixties Pop Grooves
Soul Grooves MIDI
The Progressive Foundry MIDI
The Rock Warehouse MIDI
You realise that this list is a peephole into your soul ? Musical tastes tell so much. 
(Only jesting)
Elementary, my dear Watson
Yesterday night I read many fora where musicians claim the sound of EZDrummer 2 (and other drums plugins) is better than Jamstix, at the point many use the latter just to drive EZDrummer 2 (and other drums plugins)
In my particular case, I hate any kind of editing/modding because my avatar: Happy Jamming
So I think I’ll keep my EZDrummer 2, and I’ll wait for a Jamstix rebate