Update: Slow summer of brewing for multiple reasons, but back at it. I brewed 10 gallons of IPA last weekend, pitched half with Belgian yeast, half with east coast. I was much closer on numbers, over a bit in fact. I added a tap in the house water line before the softener but after the filter, seemed to help a good deal. Checked temp consistency too, it was within a degree or so of what the BCS claimed. Still having cavitation in the mash tun though, which causes an odd stop/start pumping. I recently rebuilt my mill and set the gap at .036", I may open it a bit to see if that helps. That said I'm pretty happy with things right now.
I also picked up another kettle so I have a complete gas system as well. Hoping to do some double batches soon side by side.