A 3blade is usually shorter..so on hard landings when the nose wheel kind of flex the prop won't touch the ground.

The most obviouse..more blades more wind(same pitch/dia as 2 blades) . But there's other factors involve.
Such as a bulky fuselage designs blocking the wind...that'll slow it down.lol

lets say you want a scale cesna (fater fuse) and a 3 blade prop to make it look more scale.
using the same engine from your trainer.....I'll go with longer 2 blades.lol

More blades to spin will require more power to trun the darn thing of course.
I mean if you ever rode a multy speed bicycle you'll know the camplex theory behind all this pitch and diameter stuff.lol
i think my leg hurts more if i go to higher gears from me having to push down on the pedles harder.lol

Anyway, there's a thing call a threashold...Just becuase your engine spin at a higher and higher rmp dosn't necessary mean
it'll produce more HP. At max rpm your engine will actaully produce less HP.

Example if your engine Max RPM is 16000. It's max HP output threashold might be at 13500 rpm.