I have had a failure with my OD which is being taken care of as we speak. This has given me some insight on the straight 3-speed and the OD.
The regular 3-speed has the slow 2nd. Believe it or not I really like the slow 2nd. With the tired engine it pulls real nice in 2nd. The OD has the fast 2nd and it takes a long time to get into the power band. I like the fast 2nd but the slow 2nd is just as nice but in a different way.
With the regular 3-speed I run a steady 60-65. I don't feel I'm taxing the engine too much. With the OD I run a steady 80-85 and have done 115 a few different times.
I have driven the heck out of my OD, at least 28,000 and about 2000 without OD. It failed on me for some undetermined reason. It is at George Ashe's being rebuilt.
I have to admit, the OD is worth it's weight in gold. They are priceless if you really drive these cars.
BloodyKnuckles