If you have already bought into an Olympus system with the E500 I cannot think of any reason to consider switching to Canon unless you have sufficient funds to make a major investment into the Canon system and want to change all your kit.

a Canon user

And every one said, 'If we only live,
We too will go to sea in a Sieve,---
To the hills of the Chankly Bore!'
Far and few, far and few, Are the lands where the Jumblies live;
Their heads are green, and their hands are blue, And they went to sea in a Sieve.

Edward Lear
http://www.nonsenselit.org/Lear/ns/jumblies.html