I had 2 PA 8" subs once, had them in my surround sound speakers in my room. They were ok, nothing special. I then sold them to some kid that was my brother's best friend. But before I ditched them, I hooked them to my amp in my car and a modified dual 12 enclosure. They were decent. I know 8's aren't the best and that probably doesn't help much, but that is my experience.
If I got a good deal on a pair of 10's or 12's, I'd think of getting them.