Hi,
With a bay/res combo are you not risking additional noise when fitted with a powerful pump?
If you have separate pump/res you can fairly easily mount the pump on some sort of vibration/noise suppressing material. If you have a combo isn't the pump hard-connected directly to the res which is in turn hard-connected to the case? Or do the combos have vibration suppressing mounts to compensate?
For me a pump/res combo (dual optical bay) is a neat solution, but if it risks additional noise...well. I'd rethink.
Cheers,
Scoob.