The lug point on that year bike is 2500 RPM. I believe in 2007 it changed from 2000 RPMs. I usually stay at or above 2500. I get my best gas milage. I never see 6th unless I am about that RPM on the highway.
This is an interesting question. Didn't the overall gearing get lowered on 09> bikes or was just 6th gear? I'm thinking my 09 FLHT is at about 2200rpm at 55mph in 6th. At 60mph it's about 2600 which is a comfortable feeling but fighting to keep it there and not shift to 6th. Certainly not a lot of roll on available in 6th at 55mph....
I try to keep the rpm's above 2200. Usually shift into 6th about 55mph. At whatever speed I'm riding, if I think the motor will lug, I just downshift. Don't want to lug the motor, but see no reason to ride at 3000 rpm's all the time either at cruising speed.
i don't watch the tac much. been shifting gears on one vehicle or another for over 40 years. however i do hear it start to lug down in 6th around 60 +-, especially trying to get my fat a$$ over a hill. I'll down shift and get going again the pull it back up into 6th. We can run 65-70 here on the 4 lanes most of the time and the LEOs don't mess with you until you go over 70. so, that means we get to ride in sixth a lot. :-)