Progressive makes a very good product. I have their portable 50 amp system, and it works great. Other than someone stealing it (which I think is pretty unlikely) the only thing you should be aware of is, portable systems can't detect a broken/disconnected neutral ground wire in the shore power cord's plug, and that's not a terribly uncommon problem. They can detect an open ground in the power pedestal, but not in the shore power cord's plug. That's because the device is upstream from the plug.
I modified our portable device, so that it now connects to our system between the shore power cord and the transfer switch. Now, it's downstream from the plug. I did that, because the neutral ground wire in our plug came loose a few months ago, and when I plugged into 50 amp service and turned on two roof AC units, the electrical load imbalance caused all kinds of problems. And the EMS device was working fine.
Knowing what I know now, if I had it to do over again, I'd have bought the hard-wired unit instead of the portable unit, and saved myself a lot of trouble modifying the portable unit, and several hundred dollars in appliance damage.
Kev
, i don't want to fry my electronics, whats good and what are you using opinions please 
