It really does work quite well, though I haven't been able to test dose variance yet. I imagine it will be within .75g every time.  

Every time the grind is adjusted, the timer needs to change. I think it's not all it was advertised as but it will save broken switches and reduce waste for a lot of people and it's an incredibly easy mod.  

This mod works great, and upon reducing waste it discourages people from trying to save grinds (much to my frustration when I start to work and get a huge dump of old grinds in my portafilter). The variance is about ~.25g from what I've noticed.  

I guess the waste depends on the type of grinder.
And that's where the Anfim Super Caimano is more consistent than a big Mazzer. Mostly because of the lower speed.

But what with Barista's who need to pull singles shots? Nowadays I see it's getting rare to have singles. We still need them and use them and therefor a grinder on demand can the easiest. Certainly with 6 or 7 Barista's in rotation behind the bar (on a weekly base). Since we have brackets to rest the porta filters ; the lower speed of the machine isn't an issue anymore.
A .25g variance for a double dose meets our standards.  

How did you wire it? Did you use some spare power cables and splice them in? Looks like an interesting setup.