here's my experience for those that are interested...
flew via NYC into Montreal last week with 8 suitcases (and having fedexed 8 boxes the day before)
there was no line up, and we got into immigration straight away and met by a very friendly agent. I knew that I had to give a list of items that weren't with me but were coming in order to get the duty exemption but i had just made scrappy notes so they gave me a more official form (B4 i think) to fill out there and then. one thing i wasn't expecting was having to put values next to every item, but i just gave a ballpark figure and no-one questioned my estimate. The level of detail i went to was like 1 x painting in frame, 1 x BOSE sound dock, various items of clothing, 1 x china tea set etc etc
Had to list all my high value electronics that were with me; agent took serial numbers and gave me a 'receipt' so that if I ever get stopped at the border again, I can prove that they were brought into the country exempt. Got my stamp in passport, and he wrote the COPR number under it, then we exited without so much as a bag search.
The next bit was a bit of a hassle. I had used Parcel2Go as the cheapest way to send my boxes (8 x c20kg each for 355 GBP) but the carrier was fedex. A week after getting to Toronto still no word on the boxes. P2G don't have phone customer service - it's all live chat which you need a computer for - so it was a bit frustrating trying to find out what the status of the boxes were ( I could see they were 'Delayed at Mississagua' using the tracking tool but didn't know any more than that)
So, I took matters into my own hands and drove to the Global Sort Facility on Derry Rd out by the airport. I knew it was there as the previous day I had gone to Air Transat Cargo to pick up our cat who had gone separately. Got to Fedex and they printed out my paperwork to take to CBSA to have authorised. Note, this is in a completely separate part of the airport complex (2720 Brittania Drive) so a car is essential! Take paperwork to the office, he has a quick look and asks if i have anything else still to import otherwise my duty free exemption will be used up, i say no, so get a stamp and take the paperwork back to Fedex who release the slightly bashed boxes (although no content damage)!
Interestingly, I'm still waiting on an email from Parcel2Go telling me how to retrieve my boxes!
The cat transport was another bit of stress. We paid Passportforpets.com 455GBP to transfer a small cat from Gatwick to Toronto on an Air Transat flight. We departed a week before him to allow us time to get settled and our friend took him to the airport at 6.45am on Sunday as directed, expecting to meet a PassportforPets agent. Alas, no agent, just a very peeved Servisair cargo lady who said that he should have been there at 5.45am and they were considering not letting him on the flight! Passportforpets later said that the service I opted for didn't include a person agent handover (I thought it did as they were providing the standard transport cage) so my friend had to deal with a pretty stressful situation. in the end, they let him on the flight, and to collect him we went through the same paperwork-customs-collection process as outlined above.
So anyway, alls well that ends well, we're all here with all luggage and beginning to enjoy the city and new life!