If you pin them on the spine there will be a difference as the green followers don`t have the rear leg and that`s what makes them less stable, when you pin on the side in the groove the thickness of the front leg doesn`t matter as it does not ride in that groove.
The gen 1 magpuls work flawlessly if you take 5 mins and fit them to your mag, I bet those gen 2 magpul`s will just be slightly narrower at the sides so they are more forgiving in a tight mag body.
Lastly i`m sure there will be slight variances depending on the different mag makers anyway.Whatever works for you .