I always use Playmaker + Corner on my DMC.
Reason : My DMC is supposed to be the "engine" of my attacks, so he needs high % passing. Having that, I'd give him a corner ability too, because - high passing, and corner is about precise passing ( at least in the real life ).
Never regret it so far. Having the 2nd place ( in my team ) in assistances made.
So, it's not a bad idea ( at all ) having these 2 abilities on 1 player. Preferable on a MC or DMC, works like a charm for me