I have crossed many borders in my time and to be very honest, the Canadian border officers are the worst for me, all Canadians I think. I really think they feel inferior to the RCMP officers stationed at all border crossings, they are seen as more official by some border customs officers, well they are inferior so their feelings of inferiority are justified and take it out on the travelers (only Canadians, they are very polite to foreigners)
As far as seizing anything, I have never had anything seized and I have brought 20 knock off watches back as gifts for friends or DVD's, VCD etc. I don't think they are looking at someone carrying 20 pieces of
different articles, they are concerned with someone carrying 200 Rolex knock offs, then it is more serious.
The last time I drove to the states I was going to a shooting competition in Washington. No problem, I had driven across the border many times through Montana while transporting more than one firearm, this time was different. When I was asked where I was going I told them, then they asked if I was carrying any firearms, as they always do, except this time they were rather agitated and demanded that I get out of the Jeep.
As I mentioned, this wasn't the first time crossing at the crossing with firearms, it turned out to be the last, after that I flew, believe it or not it is easier to transport then on an airline. The Border agents instructed me to take everything from the vehicle, this wasn't all that easy because I was going for 3 weeks and camping the entire time, so I had the back of my Jeep completely packed. After unpacking all the camping supplies I opened the bolted in safe that held the 4 firearms (a pistol, an assault rifle, shot gun and long range rifle). I showed them all the required paperwork and the invitation to go to the competition all valid and orderly.
After 6 hours waiting and being treated very nicely I must say I was "Released" They refused to tell me what the issue was and told me to be on my way.
I later found out the Clinton was appearing in Washington state somewhere, they were a little concerned about a Canadian with guns I guess.