I installed the PI 50A hard-wired unit in our new TT. I'm not concerned about warranty issues because I see no way they can connect the EMS to any kind of failure and I guess mostly, I'm just not worried about those kind of things.
Having said that, I would take a close look at the Surge Guard unit next time. The PI units display is straight out of the 80's and its bright red LED's only show one parameter at a time. The display unit has a terrible viewing angle so must be mounted close to head level to be able to read it. The SG uses a modern LCD with everything available at a glance. Also, there's the fact that PI was bought out and reports of poor warranty support are cropping up all too regularly.
If a SG does everything the PI does, I would go with it instead.
All JMHO.
Scott