Tim's recommendation here is spot on.
The black dog works wonderfully on longer scale length guitars, and is perfectly capable of getting utterly, utterly filthy, with the right amp (as MDV rightly said).
Now I must admit that the higher gain pickup 'problem' of mushiness and 'over-the-topness' in baritones is not something I've been able to confirm with my own setup. I used a black dog in my 26.5-28" multiscale Wez Venables baritone and was extremely happy with the results - this was Tim's recommendation, by the way, and I thoroughly agree that it's the right pickup for you given your posts here. BUT (sorry to confuse the matter), I've recently switched the black dog for a miracle man, which I had in my gig backup ibanez, and for my style (which is less post-metal, more hardcore/thrash/grind), it hits the nail absolutely on the head. 13Gauge has just finished the instrumental recording of a 4-track EP in the studio (vocalist lost his voice, so we'll need another day to get the vox down before final mixes and mastering! Gah!), and I'm extremely happy with the sound of the MM in this axe. I didn't find any of the sonic unpleasantness that Tim mentioned to me he'd found with higher output pickups in baritones. Of course, there are an awful lot of other variables.
It must be said, though - the cleans on the black dog were superb, and an AlNiCo pickup is definitely a good idea for anything involving cleans on a baritone IMO. Absolutely gorgeous. I couldn't do them justice with my 5150-II (the clean channel is a dog), but through a Fender... WOW.
Anyway, bottom line: Black Dog is definitely the right call. Don't worry about the output (unless you have an amp with almost no gain on tap), they get plenty heavy enough :)
(the above is all relating to bridge pickups, since I don't even have a neck pickup, and wouldn't use one if I did).
Hope this helps,
Roo