There are two voltage pins on a SCART, one is the channel auto switch, and one is RGB Select. The auto switch is indeed unnecessary, but if the RGB select pin is not hooked up, your tv set will only use composite signal.
The Saturn Scart RGB cable (the official PAL one anyway) has that +9v line hooked up to both pins. If there is no +9v line in the console, the Scart cable will only output composite, since the RGB select pin will have no signal (unless your TV can manually select between rgb and composite input from a Scart cable, which is theoretically not impossible but I don't know how common it is). If you use a 110v power supply on a VA6+ saturn, you won't provide any power to the 9v pin, the RGB Select pin on the Scart will remain empty, and your display will not switch to RGB mode. This is a moot point though since the only NTSC power supplies you can use with PAL machines are the ones that have an empty hole for the fifth pin, and not all of them have that, so chances are the thing won't physically fit unless you cut off the fifth power connector pin. Plus, why the hell would you want to run a PAL machine in a 110v country anyway.
I've had saturns that had the +9v line burnt out (short circuit blew an inductor near the av output), and they did not display RGB, only composite, unless I used my own-made cable that used the +5v pin for RGB select.
NTSC Saturn scart cables are all third party (*), and most vendors on ebay have separate ntsc and ntsc+c-sync (raw sync) cables available. Those ntsc cables should work on a PAL Saturn, as long as you are not using the "raw sync" ones, which can instead damage your tv or the saturn or both (by feeding +9v dc to the composite input of your tv).
(*) the one exception is the japanese RGB21 cable which is like Scart but with a different pinout, and I don't know if it uses composite or c-sync.