My LH octaves are very different to my RH. I can use 13 a lot with my RH, and play scales etc...using 13 14 15...but with my LH I can only use 14 and 15 comfortably...even though my LH has a larger stretch. I have a 10th in RH and an uncomfrtable 11th in LH.
I find high wrist octaves awkward for a lot of things. The problem is, you hav to create the octave shape with the fingers and hit. If you want a warmer sound you can play from above and drop into the key. I personally find that for really fast scale passages in octaves I use a normal wrist position, so I can use the fingers independently from the arm, becasue that is the only way to get extreme speed. The wrist can only move so fast...but the fingers can move very fast....if yu relax everything, you can crawl up and down on 345 and if the arm is relaxed the thumb will be relaxed, and then you can just move very quickly. I suppose the wrist plays a major role here, but at the same time, it does not really, becasue ll it does is stay relaxed and support the fingers.
Hamelin has huge hands, so I don't see why he plays with a high wrist. Usually people play with a high wrist becasue of hand size issues....but he has really large hands. I am not at all convinced by his tone production though, so if he wants to poke at his octaves thats fine for him.
The LH is more prone to getting tense as well, and I find if I start to get tense, or just tired usually becasue of tension) my LH wrist will begin to rise. I try to avoid this, becasue I don't like it at all, and it feels awkward (for me).
Octaves are very personal at the end of the day
