StarDust4Ever,
The TurboGrafx16 units do not have as bad of an issue with caps as the Duos. The Duos are sitting time bombs if the caps haven't been replaced. While it is not the best sample size to make judgments by, only one-third of the 20 or so TurboGrafx16s that I have replaced caps on actually had issues caused by the caps. The two-thirds that didn't really needed the caps replaced were done so just because people like the idea that the caps have been replaced. I think some of it is paranoia carried over from the Duos. So, I don't think the cap issue with the TG16s is at an epidemic level...just something cheap and easy to do if you are inside working on one at the time.
You are dead on with the NES, SNES and Genesis. I haven't seen those needing to be replaced too often. My own Atari, Coleco Gemini, Colecovision, Genesis, and PSX all have their original caps and show no sign that they should or need to be replaced.
You are lucky with the RF connection. I have a pile of RF modulators that I have removed to perform A/V mods. Most of those don't work or don't work well. The material that they made the RCA jack from is the cheapest material I think they could find. They are either so oxidized or corroded that they fail to work. I am sure that what part of the States they were in and the humidity levels there probably had a lot to do with the oxidation and corrosion.
I also keep thinking I want to do the LED mod to the logo. Did you use an LED strip or just single LEDs?