Oh boy...... what more can we expect from a forum with such riffraff. Hot flashes? Stick a rag in it. As for you Sherlock, I would suggest staying off your meds as you are clearly in a delusional world of your own for thinking your word is law. What did you do, empirical research during those 13 years? Ahem.. If you haven't been using these systems in conjunction with a step-down then how can you even give an opinion? I've actually got 3 years over you with my Saturn and believe otherwise. Moreover when did I suggest that not using a converter will definitely cause issues? I use it as a precaution as it may very well prolong components. Not to wish it on you, but your SS may bite the dust tomorrow, mine might too, but taking the extra effort by using a system in optimal conditions is not illogical.
I'm going to give you a pass here since you obviously have an underdeveloped sense of humor and I shouldn't discriminate against disabled people.
Regarding the topic at hand, a step-down transformer, and you now wanting to be scientific and analytical, you are saying that your systems run "noticeably cooler" with one. This claim brings up a few questions:
How did you measure the temperature? Did you install thermocouples or use an infrared scope? I ask because the things put out almost no detectible heat even running without a step down (as anyone here can tell you because none of us use one except people living in 220V regions) so its not like a PC or a system with a fan or anything that just gets hot to the touch.
If my system is sitting there at room temperature and yours is at room temperature with a step down, how do you know which is cooler?What power supply are you using for the PCE? Which PCE?
What voltage is your step-down actually putting out under load?
What model of step-down transformer have you been using for the past 16 years?
It would be interesting if someone compared power supplies for Saturns. I have one JP system and one US one, but they are of different generations and the power supplies are quite different. Considering how many variations of Saturn there are (probably a dozen or more) it might be difficult to learn this info without a huge stack of the things.
Regarding polarization: Yeah, you don't need to worry. In US nearly every power cord has terminals designed to preserve polarization, but most of the time its useless or impossible to actually gain anything from it. If the first thing AC sees in a device is a DC power supply with significant voltage reduction and the entire case is plastic and it has no external grounding...then there isn't any point is polarization. If this were a medium duty drill or a toaster or something, sure.
Regarding PCEs specifically, and PSUs for them: My Duo R's PS gave up the ghost before it was ever even imported. The guy before me was using a Sega CD PSU, but I didn't like it so I used the Radio Shack shack one, 273-1771. Anyone using a US power supply should know that a step-down is beyond stupid in your case. So this makes step-downs basically useless for nearly everything pre-3DO. You're better off just buying a US power supply since if you don't have one already you'll probably need one soon as they don't last forever.
Regardless of all this technical stuff, there is a metric assload of anecdotal evidence suggesting that step down transformers are not needed for JP systems in the US. I've known many people with all sorts of imported systems from Famicoms to Saturns, PCE, PS2, Gamecube, etc etc, none of these people used a step-down transformer and none showed any sign of issue. Therefore, while you *may* be protecting your system, I think these devices amount to nothing more than snake oil. If it makes you feel comfortable then also make sure you use Slick 50, ginseng, chakra crystals, and avoid gluten while you are at it because you obviously respond very well to bullshit. If you order enough crap from infomercials you and your imported game systems might just live forever!
For what its worth, NTSC-J is also slightly different from standard NTSC. NTSC-J uses a black level of 0 IRE whereas the standard NTSC uses one of 7.5. Does anyone here recalibrate their TVs for different regions of systems? f*ck no, because nobody can even see the difference. Most people are running their PCE's stretched on 16:9 LCDs which makes everything look like ass regardless of any minor tweakings like that. Similarly the caps in your black Duo are all leaking at this point no matter what voltage its been operating with for the past 20 years.