ahk40a wroteYou should know that you are buying a service called BIS (Blackberry Internet Service) this is a relation between your provider and RIM, and if you try it you will feel and touch the difference, you will open files and data more than 500 MB over this service due to a compression used by blackberry.
I doubt that, RIM mostly compresses BBM chat messages, Facebook(and other known used sites)... it also compresses Youtube but let's not forget that with compression you will have a loss of quality. Also try downloading an mp3 file/video file/application in raw form, that can't be compressed(if so then it might turn to corrupt data/loss of quality)
Now I know they have done research and found out that BB users consume less than other phones(Android,IOS,Symbian) but they have neglected the fact that the increased usage by other phones was due to users installing more Apps(which are more available on other OS) than on the BB.