Assembly is discussed all over the place here, more often when it's used in conjunction with PBP. DT's Instant Interrupts is a prime example.
For the most part though, straight assembly is better discussed over at Microchip's forums.
But in the end, I think you'll find that, if done right, PBP is just as effective as assembly when doing almost anything...if it's done right that is. Some say that PBP is pretty wasteful in certain situations. It is...in certain situations (On Interrupt being a good example), multiple If/Then's, Select Case, those types of things. But it sure is a lot easier to do those types of things in PBP than assembly.