I own a number of custom lugged steel frames, Spectrum, Serotta, Jim Merz, very soon a Columbine, and I've seen plenty more and I can tell you this: I've *never* seen any other builder do this filing of the inside of the frame, though I hear that Alex Singer frames are made this way. It really is quite incredible to poke your fingers around inside and feel how perfectly joined the frame is.

Now that you're spoiled, you may never appreciate any other frame the same way.