I have used 375 at 45-50 seconds.. on a DK 16x14 I think the size is.
Shiny metals from my experience are harder than the brushed finishes. Also if the paper happens to stick some you don't really notice it as bad on brushed.
If you use white aluminum it works perfect and there no problems. Make sure you use a background color on the white, when doing trophies or it will look dumb in my opinion. When using the brasses and silvers you dont have to waste ink on the background fill, not that its a lot.
Sublimate the shape of the plate on the substrate too, especially for large lots. When you get them on the cutter it will make life easy.You still have to put tape on the backs of them as well. Make sure the sharp side is down on one side of you rows, with the cutter. You will use the sharp down to cut the edge of your tape no need to use scissors, dispenser or blades.
I know this was more than what you asked for but I figure I save you some time

Like most people here that do the shirts and all. I do alot of trophies plaques and custom awards. Im used to long runs and I like to save time.
Enjoy