Most surge protectors use MOVs. MOVs, if used correctly, provide for no filtering of the AC. Just simple surge protection.

As far as $$ eqp warranties, usually they are really strict in that every piece of eqp in your system has to be connected through it, including cable TV and satellite lines. Maybe hooking everything up and then taking a picture of all the connections might help. I imagine that the details of getting that money are in the "fine print." Incidentally, despite marketing claims to the contrary, people who live in thunderstorm-prone areas are, for the most part, the only ones that need to worry about surge protection. But they are cheap "insurance" for every one.