I've been looking into the polymath a little as well. How would you describe the top end? Is it really brittle and harsh? From what I've read it's got a grindy upper mid thing. What kind of bass is it packing?I haven't tried most of them. I've got the Juggernauts in two guitars and love them. I recently swapped out the Juggs in my #1 (see avatar) for some Polymaths, then swapped back to the Juggernauts. The Polymaths sounded great in the Solar I got them in (I gushed about them on here), but in my #1 they sounded really blase -- the mids were really flat and broad, filling all the available space but lacking an actual voice. The Solar was mahogany and my #1 is northern ash over swamp ash, if you believe in that sort of thing. My #1 started out with SD Nazgul/Sentient (as seen in avatar), which I hated in that but really liked in my now-sold KM6, so it might just be an eccentric guitar.
The Juggs have a couple spikes in the mids that some people dislike, but it's subtle enough it doesn't give me a cocked wah vibe and prominent enough to have a distinctive voice. I also tried the Painkiller 7 set in a KM7 but found them bright and thin. It had an evertune tho which may have contributed.
The only other BKPs I have are the 63 veneer board singles and the Stockholm HSP90s, so that's no help. I do have a custom Valravn 7 with Silos on the way that I'm excited about.