Sounds like using the all metal dust deputy should never cause a problem. At ~$120, seems like cheap insurance against this problem.
I, however, still am confused as to why a static discharge, when using the plastic cyclone, would cause a problem in the vacuum. I would expect the static build up to come from two things: (1) the tool, which is conducted through the first hose, and (2) the static electricity produced by the dust flowing through the plastic cyclone. When the charge becomes great enough, I would expect this to discharge to the second hose, then be conducted through that hose to the ground in the vacuum. I can't see why there would be a discharge that would be sent through the vac's sensitive electronics. There should be a path to ground (vac hose inlet) with a much lower resistance before the electronics.
Now perhaps if that second hose was not conductive, then maybe there's a higher chance of discharge within the vac, although one would hope that discharge would happen at the hose inlet on the vacuum, and not the electronics. Has anyone used a Festool hose between the cyclone and the vacuum and not have any problems at all?
