Check this out: http://www.modelflying.org.uk/kangar...pot_canard.htm
I added canards to my Roo since I had trouble with getting the AoA up to a high drag, nose up attitude for landnings.
They help, but not as much as I had hoped for. Biggest difference is in turnradius, I can turn alot tighter now whitout running out of elevator.
Only bad effect is that it's a bit more sensitive in pitch at high speeds.