We had this on a 23' Eliminator Eagle with a Merc 525SC and Bravo drive. It was much easier to drive with both hands on the wheel and trim buttons on the steering wheel. Boat had hydraulic assist not full hydraulic so the steering was not as smooth and easy as full hydraulic, so it was kind of tough to drive with one hand anyway.
Had it installed new in '98 that way. Two handle controller made by " In-Control", so you can use either one or as your needs vary ---- with ONE important caveat. 
I should get an In Control (Or whomever owns them now) dead pedal, then it would match my throttle pedal !!.
The real high performance guys are running with a throttleman with sticks.
Oh, are you referring to those macho-macho men who now race offshore boats in bays and on lakes ?
I prefer them as well, never thought about getting tossed out and the return, i just like the stability. i do enjoy the hand throttle on my toon though. And not to poke the bear, i believe you have more experience than i do, but shouldnt the lanyard kill switch shut the motor down before the throttle could return? not trying to argue, neither of my floats have a lanyard switch, but have been considering adding one on the jet bote.
very cool setup. some of the land speed guys (danny thompson in paticular) who are running twin engine streamliners run the same type of throttle.
A family friend of ours fabbed a setup like this up in the 80's was really cool. I've never seen a similar setup. He had a a foot pedal, and a two handle side mount shifter. One handle on the side mount ran the 3 speed and one was for the throttle if it was hooked up.My 22' Cole NH has both foot and hand.
I primarily use the foot throttle as it offers a far quicker reaction and allows for both hands on the wheel when you want to explore it's performance potential.
I use the hand throttle option for cruising, or in mondo-washing machine conditions where the foot throttle can be jerky. Also allows the driver to relax your legs and move them around more freely.
The "CAUTION Will Rogers" caveat is, in as much as the hand throttle will fully increase and decrease RPM, when you return to using the foot throttle, you MUST immediately return the hand throttle to it's lowest position. Otherwise, the foot throttle can not decrease more than the hand throttle is set for.
Obviously, this could be dangerous and why Jim Cole had me sign a ' Release of Liability' stating I was acknowledging this factor.
Hard, fast, never broken rule is --- Foot on foot throttle, hand throttle is pulled all the way back. You never use both simultaneously.
Depending on the boat, the 496 is likely the training device
A good buddy of mine @framer1 had a couple nice new 26 DCB's the first of which was a Mach with a Blue 500 , foot throttle, foot trim, which I prefer to drive with as well on a single engine setup . To stay past the porpoise speed range his motto was always " I may not be the fastest, but I NEVER let off " . He got his money's worth from that motor for sure, and the drive lived the duration of when he owned that one.
Must be a go-fast boat dealio, I've never had a hand throttle that did that haha
This Howard also has a foot throttle. Fun boat to drive and definitely requires a foot throttle at speeds to have both hands on The wheel. Also easier to catch the blower serge when shifting. There’s a reason this particular boat made a magazine cover it’s honestly a great 22’ boat.
Wasn't there one that ended up changing the prop rotation and running the drive in reverse to get it to handle right on here a few years ago ?
I didn’t think I could function with out a foot throttle on my last O/B. But the offshore controls really weren’t too far off and I learned to like them as much as the foot throttle.
