So as long as you don't mind a muddier and less defined bass end, then the higher output pickups should be just right ;)
Roo
As a dealer who has sold/installed probably around 200 7-string Bare Knuckles and many others for down-tuned 6s, I have to disagree with the popular notion around here that high-output BKPs don't excel for low tunings. While yes theoretically cleaner pickups will have a clearer sound on the low-end, there are a lot of important factors that aren't being considered here:
1) If you use a high quality amp with good speakers that is is voiced well for baritone (assuming we're talking about in a metal context not Duane Eddy stuff here) then this is a non-issue. In my personal guitars and countless of my customers' ones, pickups from the Cold Sweat, Painkiller, all the way up to the Warpig all have achieved amazing results. It's not going to be muddy or undefined if you have decent technique and good gear. I primarily play 7-strings tuned (low-to-high): ADGCFAD and with various models (Painkiller, Warpig, Cold Sweat, Miracle Man, Nailbomb).
2) Some amps, especially tube amps, respond better to high-output pickups than others. Sometimes that extra juice that is slamming the front end of the amp actually tightens things up and gives it more focus. There's a difference between distortion and output, you know? It's the same reason why 99.9% of signed metal bands use a Tube Screamer variant in front of the amp as a clean boost to get a tighter, crisper sound. With some amps, low output pickups can end up producing a very dry, unpleasant sound with high distortion settings. It is my experience with many high-end tube amps they produce better results when you can hit the front of the amp with a hot signal and then turn the 'gain' knob down, versus going in with low output and then turning up the preamp gain on the amp. It varies amp to amp, pickup to pickup, speaker to speaker, style to style.
3) It really depends amp to amp, guitar to guitar, etc. Certainly if you put a Warpig in an all mahogany guitar with a rosewood board, and then run it into a fat/loose amp you're probably not going to get great results from your low B string. However, if you ran a Cold Sweat or Painkiller which stays incredible tight and focused in mahogany guitars under heavy distortion with low tunings then you're in good shape. Especially if you're rig is setup right as I mentioned before.
4) Another factor often overlooked is strings. Another myth (IMO) is the idea that the thicker the string the better the tone. If anything, I find with downtuning the lighter the string the better the tone. When you start messing with super thick 'low B' strings, the tone becomes rounder, more mellow, muddier, with decreased attack and tightness. As string vibration decreases, a less aggressive tone is achieved. Part of that 'growl' is the string vibration. You'd be shocked at the amount of times a simple change in string gauge (or brand... companies like Elixir NanoWeb make some of the best sounding low B strings on the market) can completely save the day for a guitar's tone.
The bottom line is, I reject this rubbish about high-output BKPs not being ideal for baritones. I see and hear proof otherwise every single day with the army of baritone and 7-string guitar players I deal with. I think a much more important factor than output in gauging what works best for the low B string is the voicing of the pickup. Pickups that focus more on upper mids seem to keep the low-end tighter and more focused, regardless of output. But again, that doesn't mean thick low-mid heavy pickups like the Warpig or Miracle Man don't absolutely perform beautifully with baritones. If the rig is setup right (good amp, speakers, strings, tubes, biasing, technique, etc) all will be well.
I have a Cold Sweat in my 8-string guitar and that sounds absolutely incredible. Tight, focused, punchy low end with great attack, power, and harmonics. I could not be happier with my decision. I'm sure the Black Dog Tim recommended would have sounded good too but I knew the CS is always a winner in basswood guitars and I figured my amp (VHT Pittbull UL) would respond well with it, and low and behold the results were absolutely perfect.
I'm not trying to say Tim doesn't give superb advice, he is practically a God to me,
no one respects him more than me, but sometimes people on forums get way too caught up in absolutes and don't really know what they're talking about, like some of the posts I've been reading in this thread. There are nearly infinite variables which come into play when determining tone. When Tim gives his opinion, he is speaking generally and can't account for everything. So it's good to factor that in but also do your own research.
MF_Kitten: You know me from ss.org you should have come to me with this, you know I'd set you right ;)