http://www.ucanimport.com/
Check out this link. At the bottom of the main page there's a set of links to the various US Border Services websites and contact information and procedures.
I've used Coutts, Peace Arch and Kingsgate, BC crossings and find them all to be just fine. The only differences are on the US side, Idaho and Montana exports are managed out of Whitlash, MT US customs office and Washington exports are managed out of Blaine, Wa.
These US customs regions are like little fiefdoms with each having their own rules and hours. Here's a couple of +, - 's:
Blaine/Peace Arch - 9AM to 3PM only for exports (iirc)
Coutts - 24 hours, but they want signed-over bill of sale in advance of 72 hour wait period.
On the Canadian side I haven't seen any differences from crossing to crossing. I've always had excellent experience with Canadian customs on vehicle imports - they are pleasant and efficient when you tell them you're importing a car.
In my experience this is a dramatic contrast to the arrogant, pushy, rude (almost downright beligerant) attitude I have been subject to at Canadian border crossings.