J.J.,
Largely due to your early enthusiasm about the Thiersch Blue Line (PVC), I bought a PVC-skinned STW 7 (his current production version of the M7). At my request, Dave Pearlman used it to replace my Neumann K47 in my Pearlman TM-1 (EF14 & Dave's "Historically Accurate" BV8 transformer--as I believe he calls it). I liked it so much that I immediately had Dave build me another mic exactly the same way. These mics may not be exactly U47's, but they are close enough for me that I would always use them first because they are quite close to what I want in a U47 and--if I have to punch in a line at a different studio--I have the repeatability of being able to use exactly the same mic, since I own it. The Theirsch PVC capsules are very nice, imo.