I emailed RockyMounts, the company offering the discount, and they said that they have had no problem with this particular service and that they knew a lot of other companies that used them. Why would they expect that "no problems for them" means that the customer offering up private info is not at risk?

I started a fake registration with id.discount to see what they want. It seems that they asked for the same stuff that Home Depot or Lowes wanted, but there was some other info that leads me to believe that they have access to DEERS. Anyhow, I chose not to register.

RockyMounts does offer a 25% discount for Military, but not sure whether that's Active only or includes others.