Rick, your advice to Peter was as knowledgable, clear, and cool headed as any one could want--and I have already added it to my virtual music book--

However, if the guys Peter was with were playing an Eb and dropping down to C#m, (it would generally really be called a Dbm in that key), they were probably playing a Greek, Armenian or Klezmer tune in what is sometimes called a Hijaz scale--it is pretty much a major scale with a flatted second and flatted sixth step, and quite a popular scale--used in such favorites as "Miserlou" and "Fiddler on the Roof"--

If you accidentally find yourself among such folk as play this sort of music(it is a very popular scale)-- another chord that will come in hand is E major, or E7, (which would be considered Fb for these arcane purposes), and you can actually do very well just bouncing from the Eb to the Fb or Fb7 whenever you feel a chord change-- it even should fit in instead of the Db minor--

Also, the key often is D (alternate chord being Eb or Eb7) so the might have just been out of tune that night--