JMP, My guess would be that it's a little short on power. With that being said, Sea trial the boat with the same type of load you would normally operate it with and see how it does.
I would not sea trial it light on gas, water tank empty and two people on board . load it down.
The quickest way to add weight is with bodies(live ones are easiest
).
Whoever has it now might be swinging props that are say 15x15 instead of say a 15x17 to help it along. That would help on the hole shot but would have the motors spinning a few hundred rpms more for a normal planing cruise speed.
Let us know how it turns out.
I fished a few times with a friend on a 26' Blackwatch with a 9'6" beam . It had twin Yam. 150's on it (2 stroke SWSII"s ). I thought it would be underpowered but was pleasantly surprised that it had plenty of power. The Grady is a heavier boat though.