Many people I know who have the $25 data plan have all gone over and they only use their BlackBerry for pinning others in the office and they use an IM client. Most have taken the $40 BlackBerry data package.
Since your first few months of data are unlimited as per the promo on right now monitor your data use on your bills and make your choice accordingly. Check out Rogers.com
to view data rates as well as voice and data rates.
Enjoy your new BlackBerry.