So, I finally bought this. Thought I'd throw my thoughts up for anyone else doing research in the future. I'll add to this if I discover anything new in the future. It does feel a bit weird spending this much when the bbq itself was only $400 but I figure it'll still be useful if I upgrade the kamado. Someday I'll see a bge or primo second-hand at a steal...
I fired it up on Tuesday just to try it out, but I didn't have anything to roast with it (I did grill some lamb chops at the end so the charcoal wasn't a total waste). During the initial test I turned it on with the pit at about 75C, and set the target temp to 115C. It overshot it by about 15C and slowly came back down. I then increased it to 180C but in a few incremental steps. I was able to hit 180 spot on so that's the workflow - if turning it on early, aim lower and it'll be fine.
Yesterday we cooked another duck so I used it then. Because the duck was hanging there was no grate to clip the pit temp probe to so I just dangled it through the top vent. It held temp better than I expected, not varying more than half a degree for the whole cook (except opening the lid of course). In the screenshot below you can see the fan spinning at 4% power at 0.4 degrees below target.
The case is great. I like how (once the cables are put on the 4 winders) there's room for extra things like a battery pack, usb charger and, tbh I'm not sure what else I'd want to put in there but there is room.