Excellent work capricorn kid. Your post deserves its own thread, and not to be burried in this one. I'd welcome you to make a thread with these measurements for potential BIC PL200 vs. Klipsch RW-12D buyers.
Your graphs confirm what was expected to see in regards to the bottom end of these two subs.
Ignore the 40hz drop that shows up in your screenprints. It occurs on both pairs of subs, meaning it is a room and sub placement anomoly that is unique to your room. If you ignore the 40hz anomoly you can see the Klipsch response between 25hz and 80hz is much flatter than the PL200 response. The smoothing enabled on the SMS-1 hides the true frequency response to a degree, and I suspect is a bit inaccurate as compared to something like the omnimic, but since they were both measured by the same tool you can still definately see a difference.
The 80hz drop off on both subs can be ignored as well for the pairs tested because:
1) your crossover appears to be either 80 hz or 100hz
2) your 40hz null in your room will repeat at multiples of itself. So 40hz, 80hz, 160hz, 320hz etc.
One might say - well heck it's only several dB difference down low so why's that matter? To that I respond that 3dB requires a doubling of power, and 6dB and quadroupling of power. Having 3dB more at 20hz is like adding a second non co-located subwoofer and 6dB more is the eqivalent of running two subs double stacked. So 3dB or 6dB is a significant difference down low. Not to mention a flatter frequency response measurement is ideal for many reasons aside from ability to produce the low frequencies. If your subwoofer has a 50hz peak of 6dB over a 30hz peak (as the PL200 shows) it's as if you had two subs stacked playing a 50hz tone and only one sub playing a 30hz tone. Which tone do you think would be more pronounced? And a six dB difference in frequency response is probably about the best most of the people on this forum can hope to have without measuring gear. If your room makes that 6dB difference worse then you can really get some terribly responses. It's better to start out with the frequency response as flat as possible, and the Klipsch does that function more effectively than the BIC.
What EQ did you run the Klipsch in? Flat, Music? or Depth? In my experimentation on the Klipsch subs, the depth setting produced the flattest frequency response of any of the three modes.
Look what happens when we ignore the 40hz area null in your room! Sorry the mock up isn't more professional - but you get the idea.
That is a very solid advantage to the Klipsch in the flat frequency response department. Just as would be expected for a originally priced $600 subwoofer vs. a originally priced $300 subwoofer. And as we discussed before, the reason the RW-12D made bad noises on that heavy bass movie was that it was trying to reproduce the frequencies requested of it by the source material, while the BIC comfortably said, nope, I can't dig that deep, so I'm not even going to try. This is because the BIC PL200 employees a more agressive high pass filter in the amp accompanied with the box and driver spec/design. It's a design choice and it eeks out more spl at the expense of extension.
NOW this isn't to say the BIC PL200 is bad. To the contrary. Some might prefer this design decision ---where it stays clean at loud volumes playing demanding source material. But the Klipsch is definately more accurate to the original source, and if kept within its limits --- the more desirable sub, at least in my strong opinion.