I am using a CM-7000 with a 10 yo Panasonic CT-32SF35 TV. The CM is a good match for this set, since not only does it have S-video inputs, it also has an RF output for a 'cable descrambler box' and 2nd antenna input. Due to this flexibility, there is not much need for a analog pass through. I also have all three of the CM outputs (RF, composite, s-video) hooked up to the Panasonic. Using the picture-in-picture, it is easy to A/B the various inputs.
Comparing the s-video against the composite, the results really depend on whether the Panasonics 3D digital comb filter is enabled or not. With the comb filter turned on, I can't see much difference between the pictures. With the filter turned off, the differences are quite noticable. An easy test of this is to bring up the CMs menu. With the black lettering against the orange background, the dot crawl mess is obvious on composite, and gone with s-video. Turn the comb filter back on and the two look identical.
This would seem to indicate that the s-video doesn't buy much - because the comb filter cleans things up so well. However a quirk on the CT-32SF35 (or at least my particular unit) has been that when the comb filter is turned on, there is very audible background noise through my sound system. So it has been advantageous to use s-video as much as possible and leave the comb filter turned off.
Comparing the RF to either composite or s-video is also interesting. A test that really shows this is to bring up the CM diagnostic menu (down, down, info) and turn on the video test. This brings up a bunch of vertical and horizontal bars, and also some circles, on the screen. With the composite or s-video connection, there is a single faint repeating vertical bar to the right of the centermost vertical bars. With the RF connection, there are multiple repeating bars. I though the CM might be overloading the Panasonics tuner and put a variable attenuator in the line. Turning it all the way down to the point where noise starting appearing in the picture, the multiple bars were still there. So now I wonder if the RF modulator inside the CM may be slightly overdriven?
Speaking of the video test, I also notice that my image is shifted to the left a bit. No difference between RF/composite/s-video.
Sensitivity-wise, the CM is much better than my other converter - a Samsung SIR-T451 that I've had for a few years on a different TV. Both use the same antenna, a rooftop Winegard. Also the CM seems to recover from signal dropouts much faster than the Samsung.
One other feature that works ok is the use of the Pioneer cable box control signals. The Panasonic remote has cable box support, and Pioneer is one of the boxes they support. It only controls the power and channel up/down functions. One can do direct entry of the channel/subchannel number too. (No 'enter' button though - so after entering the digits one has to wait 3-4 seconds for the timeout to occur.) The CM volume control does not work from the Panasonic remote.
The only feature I miss on the CM is the ability to manually add (or even just display) channels that have not been found by a scan. It would be nice to enter a channel you think 'should' be there. Then turn the antenna while watching the signal strength meter to try to pick it up. It seems like it would be a trivial software change for CM to provide this...
In summary, again I think the CM-7000 is a great match to this particular set. And anyone who has a TV with s-video, but lesser comb filtering capabilities would certainly appreciate it. For high end TVs with good (e.g., 3D digital) comb filters, other boxes might perform about as well, and offer a different feature mix.