I just redid my entire home theater and 2 channel setup, and decided it was a perfect time to buy and use SST. Dumb me, because I made so many changes to the audio side (shorter/better ic's from pre to amp, etc) I can't accurately comment on how much the SST treatment improved the sound, but the sound is very improved, especially the blackening of the noise floor. However, I can easily comment on the video side (HDTV, Runco 930 120in 16:9 screen, etc), cuz not much changed there. The SST made the colors sharper and the overall picture is brighter. Makes sense, snce I'm getting better contact at the AC and cable interfaces.
Word of caution: use SST very very sparingly. I probably treated 10 ac cords and their receptacles, 15 pairs of ic's and their female jacks, a bunch of component and rgb cables, and biwired speaker wire at both ends...and used slightly more than the amount that was smeared on the cap of the jar. If you use too much you will a) waste expensive silver slurry; and b) risk shorting out a connection. Only put it on about 1/2 the shaft of the male ends of things, and ONLY on the outside edges of the jacks. Don't put it in the jacks!
Rumors are that SilClear is identical, or at least equivalent. Dunno. I was not willing to bet $40 (price diff). I didn't buy the SST extreme though ($150), just the SST.
Edit: Tom, I had the same concerns. It's not risky at all if you simply don't shove the applicator into the jacks. Half the shaft, outside rim of jacks...done. The back of your equipment will be a bit greasy, though, cuz the outside rim of the jacks are spaced very closely and you want to err on the side of keeping the applicator away from the openings.
Ted_B