I'm not familiar with CPW, but here is something you should be made aware of...
- Gray market goods, those that have no Canon USA warranty card in the box, may be refused serviced by Canon USA in the warranty period.
- And even after the warranty period, service of the gray market goods may be refused -- even when the user is willing to pay for repair services!
Both points certainly have been rigidly adhered to by Nikon USA and its warranty or post-warranty service work by Nikon USA.
Canon had not been as rigid in adherence to the policy as Nikon over the past, but Canon has, in recent years, been more active to reinforce its position on gray market goods on the web. Also, in recent years, Canon has been suing gray market retails of Canon goods.
Canon also says
Customers should also be aware that Gray Market products MAY NOT be eligible for:
X Coverage under a U.S. warranty
X U.S. promotions, including mail-in and instant rebates
X Technical support
X Membership programs and other service benefits