I got many of the old books as well and still buying them when I find them (often replacements though), but I still bought the RMC. My reason I guess is that it supports ICE and new books just seems more comfortably stable, especially if they are hardbound.
More clear information about certain obscure rules as well as new options and so on, makes it a definate for me. I started with the PDFs, till now where I just bought myself the Hardbounds as a birthday gift