From my experience with gfx overclocking and cooling:
1. Running stock - no point in doing anything
2. Ocing without volt mods - improved case airflow entirely sufficient, mem. cooling pointless.
Even TEC setup without volt mods was fruitless in case of GPU (only single digits increase on soft modded R9500->R9700, all pipes functional) not to mention no increase in mem. Oc
3. Ocing fully volt modded card – GPU overclock went up in leaps and bounds, memory oc increased 50% after adding ram sinks (50% more than without).
Suggestion? Pump some good juice through that system and it should pay you back for all your excellent efforts with some nice clocks
Kudos for having balls to try it and actually making it work
P.S. Two separate loops sounds like a splendid idea!
Jabo