I'm currently living an ungrounded lifestyle and I have the adapters everywhere. The only device I decided not to plug in is the microwave since it has a high voltage transformer and the microwave I had was very cheap. Not having a ground wire is potentially a safety issue but not in the way most people think. The ground wire just provides an alternate path to return current back to the panel in case the hot wire in the device should come loose and touch the metal case on the device. You can install gfi outlets without a ground wire but the gfi does need to be the first outlet on a branch circuit and labeled as 'no equipment ground'. You would need to figure that out by following the circuit from the panel and unless the outlet is turned off by a switch you need to turn it off at the panel while replacing the outlet. It's pretty easy to do with a screwdriver and something to trim the insulation off the wire like a wire stripper or utility knife and I would use a meter to prove the circuit is de-energized before working on it. I'm not sure what their issue is with the adapters unless they are telling the rentseeker to rewire the house with a ground wire. An ungrounded gfi is exactly the same as using a 3-2 adapter your just using the 3 hole gfi as the adapter in this case but your also getting gfi protection. Not sure if I made it clear but ground wire and gfi are two different safety concerns.