[obloquy]

I would say that there is probably an order that is of even less power than the Boldogs, hence the quote, "only less formidable than the Balrogs". I would take this to mean that the rest of the Umaiar in Morgoth's service are lesser than the Boldogs.

I don't see how that assertion follows from the quote. Please elaborate.

Formendacil: Understood. I won't harass you on the grounds of your rankings any more. However...

the Eagles and Huan, assuming that you agree with the assumption/theory that they were Maiar

It seems that Tolkien's latest feelings on the matter is that they are not Maiar. There's still the question of whether one chooses to accept as canon the late writings as presented by C. Tolkien.

I should have said that he was in a rather select category, one inhabited by Eonwe, Ilmare, Osse, Uinen, and maybe Melian as well. These are the Ainur who were very powerful and influential, obviously above their peers in terms of influence and might, but none of whom is a Vala.

And Olorin.

since in my mind Sauron is about as much greater than the average Balrog as the average Balrog is over the average Boldog.

In your mind, maybe, but it is not necessarily so. The level of power may have varied greatly even within each class of Umaiar. Furthermore, Balrogs were not made Balrogs because they couldn't live up to Sauronhood; they were Balrogs because they were Maiar of fire. They were a distinguished class of Morgoth's servants that were presumably as individual as the Istari.