<initially this post was responding to the difference between hinging and losing your feet>
OK. I never played front row, never coached, completely couch coach. Still.
Generally losing your feet is because you've gone in to the hit with your body too low, your feet too far behind you, so you hit and drop. It looks like a plank hitting the ground and the body is flat. Your beer belly hits the ground at the same time as you face-plant.
A hinge is where you might be too close at the hit and you can't take the pressure after the hit. It looks like your arse in the air as you face plant. Face plant with your arse in the air.
Seems to me to be different.
I'd add... Losing feet is possibly because you don't naturally have the strength to beat your opponent so you are maximising what you can get in the hit from gravity and good basic structure. But you've overdone it. Hinging is either a basic lack of really being on your game (happens more as guys tire), or over confidence in your strength to wrestle.
Umm, that is so belligerently insufficient it feels silly, but it sets my thoughts on things.
A LHP is going to want to wrestle. A THP is going to want to hold tight to his form, and if he's good enough target the hooker as the scrum pressure mounts. LHP it seems to me more likely to hinge, THP more likely to lose feet. Hell, guaranteed that the stats don't back me up, but the props themselves have something to do with it.
Let's take scrummaging further. In the second row (4) getting pressure behind a LHP only goes so far, because the bloke is trying to wrestle. The pressure helps, but it is possibly not where the dark arts lie. The second Row (5) behind the THP is key. You want utter push to immediately add to the weight coming from the THP. So, comparatively speaking, dynamic rower behind the LHP, big muscle bound over-sized rower behind the THP.
Breakaways are chosen for different reasons, but they also balance the weight from the row into the props. And the lock (8) ties the schmozzle together.
The scrum is actually a very exciting thing to behold. imvho.