DSG mach......

Color does not matter as all products remain translucent when removed. Waxes or sealants that advertise "For dark colors" or "light colors" just use more or less of some ingredient (darker=more oils; light colors=more polymers or other ingredient to make it more brighter and reflective). Nattys White, Blue, and Red will give you the same look, but I believe the blue and red contain more oils to give the "wet look" but from pictures I've seen they all perform about the same imho.
Waxes don't dull the paint oxidation does using a good paint cleaner (Klasse all-in-one or jeffs werkstatt Prime Strong) will remove any oxidation leaving the paint ready for some TLC. Now normally glazes (like Clearkotes VM) doesn't play well with sealants but Poorboys sealants seem to do just fine over glazes. I used PB EX-P and thought it looks great but durability was a let down to say the least. I don't use it anymore, the only sealant I use now and love the ease of use is Wolfgangs Deep gloss sealant. It's durability is better then PB EX-P and EX but not that much better (6-8 weeks), it's just soooo easy to use (both on and off) that is makes it a joy to work with. Sorry for the long post I'm done now