I'm playing a Demon Summoning / Dark Miasma MM right now and I would definitely recommend it. Like you, I knew from the onset that I did not want a "fire and forget" type of character. I wanted as many active powers as possible and I wanted to fight alongside my henchmen, rather than support them from the sidelines. I am taking and slotting all 3 whip attack powers and don't find them lacking at all. Between the whip attacks and the control/debuff heavy Dark Miasma, you have a very versatile character complete with healing/resurrection, debuffs, and melee/ranged/aoe attacks. And we haven't even gotten into what the demons are capable of. There are times when I forget that I'm playing a mastermind, I have so many options.
It probably isn't optimal (in fact, it almost certainly isn't), but it's a lot of fun, and hey, that's what video games are all about, right?
