Im a proud owner of two trainer high wing planes where the bottom of the wing is flat. My girlfriend bought me a seagull boomerang for xmas and the bottom of the wing is not flat i just want to know what are the pro's (if any) and con's (if any) of having the bottom of the wing curved this way?

Also are these harder to fly than a seagull arising star?

http://aabt.co.uk/prd338-1189.htm