I would have no reservations about cancelling. The only way that you as a customer can influence anything is with your wallet. If you're happy to have releases like this then go ahead, but otherwise register your dissatisfaction by not buying it. How else are we to make a difference to future releases, except by prompting retailers to complain to the distributors?
And yes, it's a shame when a class retailer like K2DVD takes the brunt, because it's not their fault at all, but in the long term they certainly won't be stuck with any cancelled copies, and if anything they will emerge from all of this with MORE customers thanks to their demonstration of excellent CS. I for one will certainly be confident in ordering from them again.
It's really quite simple - if you're happy with the product, or simply want to support the retailer, go ahead with the order. If you're not happy with how the product turned out, and you don't want other products to turn out that way, don't accept it. What other power of vote do you have?