You can start with the two articles here:

[Link: hifi-remote.com]

They are more geared towards decoding Pronto hex codes, but in the process explains the two protocols. "Pulse Width Method" describes NEC protocol and "Bi-phase Method" describes RC5.

One disadvantage I can think of for RC5 is that it uses toggle bit, and that makes it difficult for learning remotes to learn the signals. They will learn the signals, but most will only be able to learn one of two alternating signal and will work intermittently with some functions.