@Heraclea
I've tried /MC on multiple blaster primaries.
In the end, the one I like and kept, is DP/.
First, MC is fun, but it is a bit of a mix and match. It has unique flare and fun powers, but I do not consider it extremely potent. When I rolled my DP/MC, it was with full knowledge that this would be my inexpensive relaxing toon, which I play at 0/3 - 1/3.
I have it kitted, but with inexpensive sets. I main her in IP doing tip missions and inviting anyone along, her story is that IP is her home and she stays mainly there.
In short, everything I paired with /MC was ok, but the theme was what made it stick. The powers are not quite synergistic, the mitigation is good but not great, and I settled on a casual relaxing toon.
That said, I'm sure if I focused on her like I did iBlap, my water/elec and went 700mill+, she would be a monster. What stopped me was the slightly disjointed way the powers in MC are, not quite a smooth gel.