OK, maybe a stupid question, but I'll ask... I run two B1 RH drives and counter rotating props. One drive runs in forward (stbd), the other in reverse (port). I was wondering if swapping the drive locations (port->stbd and stbd->port) annually might extend their service life. It would change the gears faces (fwd vs rev) they ran on. After removing drives annually for alignment inspection, etc., does anybody swap the port and starboard location? Advantage? Diasadvantage?

Sounds like a pretty good idea to me.
When we rebuild SSM drives we swap the gears so the opposite side is loaded.

I have swapped the upper and lower gears on a single engine bravo to put a even amt of stress/wear on them too,i thinmk its a good idea,if i had a twin,i'd swap them side to side annually too,smitty

Yes. Spread the load around to the fresh gears.

And there is no such thing as a RH B1. They are "ambidextrous". Just put it in the upper gear or lower gear to get the desired rotation.

I assume you have changed your shift linkage at the dash so that both levers go forward for the boat to go forward? Please say yes.