Yes, familiar with the WE 407. Tried it, years ago, upon the suggestion of Oliver, and it sounded (at least to me) thin and glassy. I also assume that the Telefunken/USA "VF14K" glass tube-within-a-steel-tube jacket they are selling is that tube. Someone correct me if I am wrong and you know for certain what that tube is.
I guess, the 407's appeal is primarily that it requires no major power supply changes from Neumann's original VF14 set-up, and, aside of tube socket changes, (when not using Telefunken/USA's tube) that must have been an appealing consideration for all who tried it.
All things being equal, the EF14 or UF14 solution to the VF14 shortage remains the sonically more appealing work-around, despite its sonic shortcomings
A postscript: a Finnish fellow just emailed me that he has three new-in-box VF14s for sale. This on top of various collectors who sit on hundreds or more of these things...
