I would avoid trochoidal for dibond. I was able to cut it on my mpcnc in one pass for 3mm dibond, 14 mm/s and the 660 turned down, later the 611 turned pretty far down. Single flute cutter. You gotta go pretty fast for a lot of plastics.
Taking off the first layer, then doing the core works too, but takes a lot of extra programming, but the aluminum layers are thin enough to go a little faster.