I felt that the weight distribution would be better on the transom. I do not believe the swim platform is strong enough. Yes, the arms could be made longer to get the dingy up to the same height, if mounted on the platform. To tell the truth, I never really considered the swim platform. My dingy is heavy, with the fuel tank and 15hp and other items. I also put an aluminum backing plate inside the transom. There was an open space outboard the water tanks on both sides for me to get in there, for the thru bolts and the backing plate.
Further more, if you stand on your swim platform and gently jump up and down, you will notice that your platform does give a little. Not meaning it is loose, but it will vibrate to your jumping. I personally would not trust it...mounted there.
You have to also consider, the fact that you might forget to pull the drain plug in the dingy, and wake up one morning, and see several gallons of water in it....which is alot of weight. Yes, I did this...only once.
By the way, Bob Greenhaus, Gadabaut is officially for sale. My 50 year boat career is over. It is time for me to learn to snow ski and do something else. Are you really shopping for another GB?