Hi Greg

Thanks for the speedy response. I will try and get some video examples of the two settings. Before that, a couple of things I’d point out:
I always set up my embouchure the same before playing. As I play into the top half of the stave, my top lip settles (sometimes consciously, sometimes not) to one of the two positions. Since Elvis gives me better range and flexibility, the temptation is to allow this to happen so I can play more. Morrison is probably a slightly better/bigger sound but I struggle to control the corners.
It’s very hard to say if there’s any difference in tension between the two settings. Allegro is right at the edge of my ability so both settings can at times be effortless. I can play the moderato Singing C exercises on either setting with no discernable difference.

Videos to follow – watch this space!