I have used the Mec 111 - of course without the extended hook, and it is fine. Comes up second hand a fair bit so accessible at a reasonable price. You lose the rubber pips occasionally but can be replaced.
The Tech Hro - not used but again should do the job without the hook. Looks a nice piece of kit!
The SKP would be my choice of the 3 as you are paying for bits you cant use on the other two, unless you get them 2nd hand.
They come up occasionally second hand but fly out the door before you can PM. Which says something in itself.
I am only learning HFT - but too be honest most of the positions I find myself in to shoot doing HFT prone the butt hook goes no where near my shoulder - perhaps that's why I miss a lot
I hear some are going back to basics with rowan or bisley adjustable rubber ones!