Combines 2 speed cylinder setting on corn

I have a 7720-Titan i run in the low speed on corn

thats right,run it on low. high speed will crack it and break up the cobs too much. for dry corn you want mostly whole cobs in the walker area w_ no corn attached. cyl. speed and concave clearance are the key.

I have a 7720 with a two speed cylinder and find that if I run in the low range when the speed is in both ranges that the belts last longer since they are running faster.

I don't know anything about a 7720, but I agree with Deereman that the major difference you will see is with the belt. I would set the cylinder speed you want and then look at the belt in both cases. Pick the one that has the variable speed sheaves in a more central position. In general, I would say it is better to be in the lower side of the gearbox whenever possible, but not if it has the variable sheaves maxed out which might allow the belt to slip. Just some thoughts.

We have an 8820 T2 and if I recall correctly we usually run ~ 350 to 450 on the cylinder speed when doing corn.