Ran the first test of the controller today. Bearing in mind I'm using the first stab at PID settings it went really well. I think it averaged running about 5 degrees up on the target temp with swings typically within 10 degrees of target.
It was quite a windy day and there were a couple of upward swings of slightly greater magnitude but always within 15 degrees which happened at windy times. The controller behaved perfectly at these times so I think these spikes were caused by draft getting into the closed vents.
I find the WSM does like to spike if you're not careful so wasn't to surprised, tweaking the exhaust vent a tny bit kept the temps locked in very tightly.
I'll play some more soon but for now here are a couple of pics.