I would also guess something not too hot would work better. For unknown reasons people always go with superhot pickups on superlow tunings - IMO the lower you go the cleaner you want the pickup to be. Keep in mind you can always boost/dirty a signal with an Overdrive, but you cannot clean it up!!!
And since you're a Meshuggah fan I might point out that when they were still using 7-string Universes both players used to try to reduce the outputs on their DiMarzios to make the signal clearer by putting tape and stuff on them (no joke!).
So Cold Sweat or Black Dog should both work well.
There is some truth to this, adn I find that in drop B on 25.5 guitars the best results in terms of hitting your pre hard *enough* with a pickup that has a percussive and thick, saturated voicing but is still clear comes, generally speaking in the BK range, from the mid-high output pickups. The main 2 kinds I use are ceramics with 15ish and 16ish k dcr (Aftermaths and C-Bombs are what I've pretty much settled on). I've taken those down to drop A without trouble, never bothered tuning lower on my main guitars (which is mainly a scale/string gauge thing).
Too much power and you start to drive low frequencies a little too hard/highs not enough and things can get muddy. For my taste at least. I like precision. Its not really a problem down to, say, c#/c, but start to get lower and you start to hear the 'hot' and 'ultra-hot' pickups diverge in clarity (likewise A5 and ceramic start to seperate in clarity and tightness quite a bit in the same sort of region, in my experience, which is primarily with the NB and WP from the bk A5 conteporaries).
Meshuggah now use lundgren M7s and M8s: really hot pickups, so I dont know if they still do anything to reduce their power. If they were trying to get ultra-clear detuned sounds from dimarzios, I can see why they'd have to pull a few tricks! But I'm led to believe that lundgren are at least of the same order of magnitude of quality as BK, so perhaps they retain clarity and power as the high output BKs do. I dunno, I havent tried them.
The PK is hotter than the cold sweat, it has a high mid spike that gives it extreme note definition, but some (including me) consider 'spikey', LOTS of mids and a fair bit of treble against what you might call 'enough' bass to keep things heavy, and its very tight.
The CS is brighter, more open and organic with similar note definition without the spikeyness, less mids, I thnk it has less bass, and is more dynamic and responsive. If you wanted to do the same sort of thing in a higher tuning (like in A1 - C#1 or so) then the PK would be a good choice too, but while it detunes (to more conventional ranges!) really well, I think as low as youre going youre going to need all the top end and clarity you can get, and the CS is going to be the way to do it - I'd anticipate a tonal ballance thats more within what you ecxpect (very heavy, still defined) from the brighter pickup, where the PK may still kick out too much in the lows and have a bit much power and leave you with too much low end drive, when that extremely low.
