What is the measurement of your boat across the top at the oarlocks? I find that even on my widest boat (my Willie) the longest oars I need are nine footers. But this is a very personal thing for a lot of people including myself, it's your connection to the water man, and it should feel just right to you.
Many Colorado River dories sport 10-foot oars. The added length provides added leverage in heavy water. Many Rogue dories sport 9-footers. I have used 9-footers on the Rogue but they can get in the way in tight quarters.
I used 8 1/2' oars on my 17' Tatman. I peferred those over the 9' as they were quicker to move. I found over the years that I prefered quick little short strokes as opposed to long strokes when rowing. Also, I kept the oars close together at the handles rather than shoulder width as I see a lot of people rowing. I preferred the oars to come in to me at shoulder height rather than lower as a lot of people do.
Oar length is then a matter of rowing style as well as boat width. I find the closer I keep the handles to each other the better leverage I have. I have seen at least one really good boatman who rowed with his handles crossed like a scull. Even more leverage that way.
Regardless of oar length if you crab one, you will end up in the back of your boat. I have done that more than once. Always got a great laugh out of the other guys seeing me on my back in the back of my boat.......
I think your right on the money with your thoughts Herb. My oar length has shrunk every year I have rowed and even now I am starting to think my 9'er's are too long. One of my buddies who has been guiding on the Upper Klamath for 25 years has shown me over and over again that short quick strokes with short oars are more efficient then taking long power stokes. I never could understand why he could catch much smaller eddies then I ever could till I started watching him row closer. The turnover on his stokes were two to three times faster then mine and I feel like he was getting more per stroke then I was. The other area where short oars rule is on more technical water, there simply isn't as much oar sticking out to get hung up and snag stuff, they are also easier ship and tuck in when running tighter chutes.
I also row with my handles close together, like three to four inches, sometimes less. To me you are just asking for a shoulder injury rowing with your arms way apart.