The biggest difference is in features: the v93 has a bass rolloff switch, and -10 db pad. It also comes with a shockmount. The additional goodies WAY more than justify the extra $50. Everyone should have at least one mic with a bass rolloff and/or a pad. There's no way around it. Unless you like mud.
Sonically, the major differences are in the transformer and the housing. Both impart the 67 with a unique character. Forward. Aggressive. Big. The 93, on the other hand, is transformerless and very traditional in most every other sense.
They're both great mics, but I must admit that I'm starting to grow tired of the amount of bass-cutting I have to do on my 67 tracks. The 93 has a very usefull bass rolloff. It does exactly what it's supposed to do. Tracks come out clean and accurate. Unpretenteous.
The 67, to me, is one of the best voiceover mics that no one knows about. And ist's awesome for vocals. Just understand that it is a little more high-maintenance.