I've been inspired by Jon Stockman's tone lately, look him up on YouTube. He plays a 6 string Warwick with dual humbuckers through a Darkglass B7K and it sounds monstrously heavy.
I've always been looking at single coil jazz style basses for these grindy sounds, but now I believe double 'buckers are where it's at. I've been investigating a range of low-midrange basses lately from Warwick, Spector, Schecter, Traben and G&L. Any of these will deliver, especially when put through the B3K/B7K, which has now become the de facto preamp pedal for the djenty bassist!
The Warwick Rockbass Streamer Std is my first step in these experiments, it gets the sound although the pickups are really low output which I'm currently fixing with a boost pedal. A Traben Chaos is next up with its dual MM pickups. You say you don't like MM humbuckers, but try a bass with two of them and you might change your mind!
You should check out the Dingwall NG-2 too, especially if you're a fan of Periphery!