I use a Guarneri chinrest and tried many including flesch model, teka, etc, thought this would be a more ergonomically comfortable design but turn out it wasn't for me.
I place my jaw closer to the tailpiece, and over the hump(play SR less with a sponge/rubberband, violin sits on collar bone), was ok with the Guarneri model but with this one, the upward curvature close to the "hump" is cutting my jaw which is painful, yes it is very stable and comfortable if you place your jaw exactly inside the bowl.
give it to my friend after one week, he uses an SR and thinks it is comfortable.
good product for the price, after all, CG made it well with nice texture and smooth polish and no sign of noticeable artificial chemical treatment, the edge can improve though, making it smoother.
personally recommend the Guarneri model though, more versatile, just my own opinion