Interesting number crunching, I think I'll switch to the Adjusted Targeting slotting you mentioned for my Bane. I mostly play my Bane at 50 and I'm going for the Spiritual (recharge) Alpha Slot tree so if I make it to the end the differences in recharge times should be gone.
I've also decided to do something similar with Surveillance, slotting a Recharge IO and a Analyze Weakness Acc/Rech IO (along with the -res proc).