I use counterbalance on all oars > 9'. I'm not 78, but I am 60 and I want to be oaring at 78!! been doing it for 39 years on all kinds of boats. At some point it seems like tennis (or oarsman) elbow will hit you and counterbalance and oar rights help with that. You have to keep from aggravating it so it will heal. Young guys always have the strongest opinions
Anyways. This guy makes amazing oar locks for all sizes of frame tubes.
Raft frame, Cataraft, Cataraft frame, Rowframe, and Whitewater Equipment
The nice thing is that they extend past the midline of the frame and give you an extra 8" of leverage on the balance point. This works pretty well if you are running a lighter oar on the shorter boat. They can extend past the boat if you have a wide frame, which can hit in tight slots--I have had it happen. An 8 foot oar can be as bad as swinging an 11 foot oar if it isn't balanced properly. And it is more strokes per hour!!
Sinking counter-balanced oars is a problem. I get the foam tubes (looks like kids pool weenies) with the large size center. Put 2-3 feet of these on oars on the side upstream of the oarlock and wrap with electricians tape. Works great, floats the oar, and is a good cushion if it hits you and when resting below knees.
I like the Cataraft oars (seem lighter), but Sawyers are good too. Good luck.