Electronic – Energized circuit in a 3M Static Shielding Bag (silver color)

Keep in mind that what is generally considered "anti-static" doesn't mean ESD safe. What is typically considered "anti-static" are those pink/lightly colored bags which prevent buildup of charge. These aren't really conductive at all, maybe the ever so slightest bit of conductivity and I doubt your board will run into any issues with shorts and such (keep in mind Joe's comments). However, these bags do not prevent an external ESD source (say, your charged finger tips) from zapping a chip on the board.

ESD bags or static-shielded bags (silvery colored) are designed to be fully ESD safe, though as you've noted they do have the caveat of being slightly conductive. I took my multimeter (datasheet claims max range of 40 Meg Ohms) and tried to measure the resistivity and couldn't get any readings on a spare ESD bag I had until the probes physically touched each other. Your mileage may vary, but it will most likely be ok from a conductivity/electrical point of view. Again, keep Joe's comments in mind about other factors which may matter.

As an aside, you might be able to get away without using ESD shielding bags/anti-static bags at all depending on what other packaging you have.

I have not seen these before, and I can see issues for certain work environments in that there isn't really any foot protection against falling objects and crushing so OSHA (in the US) might have an issue in some environments.

What I can speak to is that often gowning rooms also provide socks as well as the ESD smocks and particles containment bunny suits. So it's possible that you could use your standard socks (especially if you've passed ESD testing at the metering stations) with your present socks and heel grounder solution. But you have the fall back on ESD socks.

If you are in a ESD controlled environment, then presumably you have a regular schedule of testing that you have to go through. Your ESD people should be able to quickly evaluate that.