realtor.com vs the MLS (need a rec)

[Geoff Miller]

I read in the beginner book on this site that when you search realtor.com you are actually searching the MLS. But I've also read that realtor.com doesn't show the listings as fast as the MLS. I have also read that it isn't a complete listing of the MLS. Is it even worth using? Or will you miss out on good deals because it is updated too slowly?

Also, what about redfin or realtytrac?

Basically what I'm looking for is a recommendation on how to efficiently get all MLS listings in real time. A pay site is ok with me if it cuts down on the time.