Thanks for both answers: I'll give them a shot. And Jacob, any suggestions on trustworthy sources for other stuff would be great.
I'm using them in my Unico, and I prefer them to the stock tubes and the other tubes I've tried(RCA Clear Tops, cryoed Radiotechnique, EH). I have not compared them to earlier Mullards. I bought them from Mr. Stereo here on Audiogon. Since tubes allow you to tailor the sound to suit your ears, why not try them?
They don't have the richness of other earlier mullards or the tung sol black glass, and don't have the extension of the telefunkens either. There are a lot of choices in 12au7s. The late Mullards are better than current stuff but really can be bettered even in that price range regardless of tastes...
For reasonably priced tubes instead of the reference ones I just mentioned, check out Westinghouse and valvo, or run your tastes by one of the small tube gurus from audiogon for some rarer selections (I can recommend several I trust if you like).