Did a bit of playing around. I tried various values and types of capacitors across the shunt. The biggest change I saw was with a 1 uF polyester cap; the 2000 sample average for CPUburn's current draw dropped by 0.014%.
Connecting the inverting input bypass cap to the output is a good concept to know. One of my early versions, with the inverting input bypassed to ground, had some ugly feedback problems. I moved/replaced the filter caps as per your suggestion, using 4.7 nF ceramics (largest I had in 0805, which is all there was room for). Results: average current reading down 0.03%, population standard deviation down 0.72%. :shrug:
As for the rest (up too late to quote), I'll be making multiple prototypes and versions, anyway, so, I'm open to doing the building. I don't think there's any need for a watt output - it's easier and cheaper to do the multiplication in software.
Mmmm, laser trimmed resistors...
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