I don't really get how your source can be reliable if it is not a friend?
But anyway, back to the main topic: Marquis and Mecke reagent are both good for testing MDMC, although they are not perfect. Marquis should turn yellow with some fizzling, Mecke will become a medium shade of brown (not very dark brown). In my opinion, if you have the test kits it would be very stupid to go about without using them. You could also describe the appearance, properties and smell of the powder. Nobody will be able to identify with 100 per cent certainty of course, but in combination with the test results it should be enough to make an educated guess.