Check out the section on using Overdrive or not. I don't use it, as I much prefer manually shifting when driving hills or under wet conditions. I'm not exactly wild about the gearing, but it does its job. I don't have a Banks system so can't say anything about that, except that this thing drives like a bus, because...it's a bus. If it was a truck, my expectations would be entirely different.
I won't be changing this one until or unless I find some reason to be driving in those conditions consistently enough to matter. But if you do decide to do it, please let me know your opinion! never let it be said I ignored a possible mod