Hello,
I've been using a set of Psvane 12at7's in a MP-1 Mk ii and I find them to be detailed and neutral - currently have about 30 hours on a ZYX Universe II.
Prior to this I was using RCA black plates which I found to be a bit richer sounding but not as detailed. I had used those with a Shelter 901.
To me, the Psvane's don't get in the way of the recording as I consider these my "fall back tubes" as I try to compare to other tube types.