I know this is a rather old post, but I figured I'd reply anyways. I'm currently the sole owner of a Dagstar in the U.S., I bought it in July from Roger, one of the first few he made. I'd been on the lookout for a Darkstar pickup for a while, but with their prices becoming increasing out of reach, I was elated to find someone else taking on the design. The fact that Roger redesigned it to have a smaller footprint, yet retain (or come as close to as possible) the tonal characteristics of the old Bi-Sonics, was a big plus for me. I was planning on installing it in a Jazz bass, and the normal darkstars are so large that I was a bit wary of performing so much routing incase I ever wanted to return it to stock. Here's the Dagstar installed in my bass:
I mostly sought out these pickups and put it in a Jazz bass due to my huge love for Berry Oakley of the Allmans, as well as Jack Casady. I didn't get deep into the Dead until earlier this past year, so it wasn't until after I got it that I learned of Phil's use of the Starfire and Bi-sonics in the EB-0. Anyways, the pickups produce a very broad, massive sound. Not too concentrated on any frequencies, but very clear throughout the spectrum. They can drive a low powered tube amp pretty quickly, as they definitely have a decently hot output. My main rig is a Sunn 2000s into 4 JBL K140s, and it produces a beautifully articulate and crisp tone when paired with this bass. Like I said, it can drive the amp into overdrive pretty quickly, so if I want to be loud and retain that cleanness I'll switch over to a Bassman 300pro. The Dagstars are beautifully made, really a work of art. They also fit under the original pickup covers (though I usually put on a P-bass cover, it fits a bit better) if you want to rest your hand and play pick style closer to the neck to get a rounder tone. Anyways, I'd highly recommend these pickups, they're truly fantastic. I've never really gone to cop Phil's tone, but with the right strings and style, I'm sure they could just as well as any other pickup in the Bi-sonic family.