So I don't know much on Glenn Vilppu's technique so I look it up online. This video on Youtube by Proko may be helpful on his technique as it is Glenn Vilppu himself drawing. What I see different is he does stronger and repeated curves or smaller, especially when he's working with pen.
On study reccomendations, learn his first, then try it on your own then learn the other's then try his on your own. Then analyze what you like of each and don't like and see what parts to use for your own gestures. I mainly know Michael Hampton for his more advance yet simplified and useful anatomy. Most of his I know are useful for fleshing out your gestures. I think he has done content for ImagineFX magnazine. So even if you really like Glenn Vilppu's gestures, you can develop them further with Michael's.
If you are struggling to learn Glen Vilppu's then try the Michael's. But I would give them some serious time first. I highly recommend to begin with longer drawings to get familiar with the technique. Then slowly pick shorter and shorter times till you're actually working on 1 min and 30sec drawings.