PG RSD subs are geared well for low frequency response. They do lack mechanical throw to get really loud though, and a 10" version doesn't help the cause. They aren't very good for high frequency response either, very muddy, well not so much muddy as just noisy and incoherent. I ran the 12" version for a little while, couldn't run the thing above 60Hz without pissing me off. It was great down low though, could dig down to 30Hz sealed no problem, even in too small of a box. Output wasn't that high though, pretty low efficiency sub. They are geared to take a thermal beating, so you can throw a ton of wattage at them. It just won't make good use of it at all though, lots of thermal and mechanical waste.
The newer RSD Comp version is a nicer sub and would be my preferred choice sticking to the current PG subs.
The problem is that there is a TON of subs on the market, so your choices are vast and many of those choices are superior to the old RSD subs.
The RSD sub is geared for large enclosures. Porting is pointless unless you want to run a tiny box (relative to the sub's specs) and a very high tune frequency and make a very peaky SPL setup.
SQ? Not even close. I will agree they are competent below 60Hz and don't do anything terribly wrong under 60Hz, but that's about it.
