the Prime amps like the R-series, I dont know, but my P-series amps were under water in Katrina for about a day and are still working great in the Blazer over 5 years later. So yes Id say that they are reliable
Rockford amps are great! That's all I have ran for 10 years, I've had the old punch series, and power series amps, and a new punch and power series. What they lack in EQ adjustability in something like a JL amp, they make up for in raw power. I've never seen a RF amp that was overrated, most are very underrated. My T10001BD would throwdown over 1500w all day long.
Our Rockford rep told us that the prime series amps are just re badged lightning audio storm series. I've tried that R500-1 in a few vehicles and noticed if you pound on it doesn't like to be ran at 2ohms and starts cutting out. If I were you I would move up to a P300-1, there about the same price and will handle 2ohms better. I personally am running a new T500-1CP at 1ohm pushing out 795watts on 2 10" T1's and I couldn't be happier.