"high thrust" means the prop turns slower, nothing more.

Horsepower, on the other hand, MEANS thrust multiplied by rpm.

you are right, hp is hp and 15 of 'em is more than 9.9 of 'em.

"high thrust" vs hp is the old sales technique, "If you can't dazzle them with
brilliance, baffle them with bull****."

hp is hp.

I own a 22' Grady White with a 225 Yamaha. I need to replace the old
kicker. This engine main purpose is to get me home if the main one breaks
down. I was told that the 4 stroke 9.9hp High Thrust is a better outboard
choice than the 15hp. I cannot understand why an engine that has 33% more
hp would be not one to choose. Is the 9.9 High Thrust the best choice?
Jim