The thing that would bother me, is the 'one claim' clause that people have mentioned.
Many repairs (most?) come under a standard charge, if sent back to Canon, which is less than $350
So, the camera develops a fault after 18 months, the original (Canon) warranty has finished and the repair will cost $250. What do you do?
Claim on the extended warranty and so get it repaired at no additional cost? Then you have just paid $350 for a $250 repair and now have no warranty remaining.
Send it to Canon, pay the $250 and keep your extended warranty active for the remaining two and a half years, in case something really expensive goes wrong? What if nothing else goes wrong and you have paid for a repair you didn't need to. You are now down $600 and had the one repair.
The warranty will be handy if you get a total loss, but otherwise will likely be a waste of money. If you use it for a normal repair, it will likely cost more than the repair would have anyway.
Even with a total loss, insurance is going to be more effective because you can claim more than once, so you still have protection.