I don't have any info on those engine mounted ski pulls....But I can talk about the POSITION of the ski pull; MY father's deep-hull, family style jetboat back in the 70's was pulled all over the lake when skiers were cutting back and forth. The hook was on the transom. This boat had a 22* vee and 3 strakes per side. It weighed approx' 2800 lbs.
My CVX-20 Jet has a 18* vee with a pad-bottom and only 2 strakes and weighs 2200......I was a little worried about it....But it had the ski-pull mounted in front of the engine at the back of the backseat(Basically, the center of gravity).....It seemed to be a good ski-boat but I only drove when my friends kids were Kneeboarding.
After 4 years I convinced a friend who was a "good" skier to try skiing behind it....First he pulled me. and when we stopped mentioned the boat didn't get pulled around a lot...So he gets in the water and gets his double high-wrap ski on...Then he holds his hand up and says, "Don't start yet!" and starts in on that mental-prepping crap- tilting his head back and forth like he's running the course in his head.....And I start wondering what the heck have I got myself into?!
Start pulling him and the observer (Kid who was typical "Slalom is an old mans game/ Wakeboarding is it dude!" youngster- Never actually seen a real slalom skier) suddenly yells "Holy crap!!" I glance at him and see my friend, head 18" off the water, just completing his turn on the left...Glance forward (Clear), check the speed (Good) and glance to the right and...He's completing his turn on the right.....
Turns out that he met his future wife on the >>>collegiate ski team<<< at Sacramento state U......He stated that he would give my boat an 8 out of 10, and would never hesitate to take a ride behind it...He actually owned a marina at the time and 4 different makes of DD ski boats(rentals). The boat did not get pulled around...I have since had a few others drive it while pulling me and one other very good slalom skier take a pull and they all reacted with surprise at the tracking.
Sorry for the long story- if you were there you would have been cracking up at all of this.....Main thing is- Get the ski pull in FRONT of the engine at the center of gravity and the boat will track true- better whether your slaloming, kneeboarding or wakeboarding.