Jeff,
It has got to sound good, the Neuman diaphram alone should do the trick, I mean it has 40% more volume than the 6072/12AU7 of the 251, C12 and C 28s, so the SN 'should' be better. I see it as a C 12 with a Neumann cap. I am just as interested in the 251 F, it has the polar pattern on the mic, not like those chick mics with the selecter on the PSU which gives a little less low end (which is why they call them chick mics).
But $1,300. for a mic like that is great.