RE: APC vs MA Props
Master aircrew do a range of props, some flex more than others. I've been recently using the s2 (old name,schimiter prop),so called because it resembles aschimeter sword.
The reson for this choice is it looks similar to an apc,It doesn't flex as much as the k series,its more resistant to nose overs not breakingand best, its cheap and black so it has alot going for it.
Now saying this, I've only run theseprops on my warbirds with much success but I have yet to try on a fast plane,like the magnum. I do have a 9x7 to try when eventually the current apc 9x7 breaks so will let you know,
However I'm sure this prop is only designed for 17k?
Saying its cheap is in respect to the larger apc's.