I'm a scent junkie and use them throughout the early bow and gun season.
I do not buy into the "cover scent" stuff. The last three deer I have taken with either rifle or bow have come in, under 30 yards, while I was smoking a cigarette (figuring that it was late enough in the morning and I was going to knock off for breakfast).
I do use curiosity and attractant scents.
I will say that I can not tell you that they absolutely bring in deer, BUT I can say that they do not "chase away" at least the deer that came in and ended up in my freezer. So for me "I think they help" so I continue to use them.
In the early bow season I use curiosity scents in the form of the Tinks smoke sticks or Remington Apple sticks. I also put out feed (mixed seed and corn) and apples, salt blocks (apple, acorn and corn flavoured), plus bury the loose minerals (like deer crack etc).
Again in the early bow but closer to the rut (so this time of year) I add deer urine to the loose minerals.
As the rut comes on I add in the doe estrus scents - like you, in Ontario we have to use synthetic. I'm not overly brand loyal. I use Code Blue, Tinks X69, Estrous smoke sticks (there is a number of different brands but they all have the same patent number - so don't matter what it says on the pack) and just recently Monette pheromones mixed with doe urine.
I will add however, that as a vendor the suppliers usually kick me some "free samples". If I had to dump the funds from my wallet I might cut back, but not totally eliminate my attractant scent usage.
Like I said, "I believe" it works and have no evidence to show that it "keeps deer away" (it may well keep away more than it attracts ??), but where I hunt deer are not travelling from their bedding area to an AG field so I need to give them "some reason" to enter my shooting lanes.
The deer in my area are well familiar with "people" so I don't think they are spooked if they "smell human" - at least no where near as much as the makers of scent control would have you believe.
Maybe if you hunt somewhere with incredible amounts of "hunting pressure" the deer are more spooked - if bambi gets shot at a few times he might start equating human scent with danger, but in most parts of Canada that just isn't the case - an enclosed deer ranch in Texas might be different...
Last note - I "party hunt" with one other guy. He doesn't use any attractants. Our stands are a couple hundred yards apart (at least in the bow seasons). In the last 5 years I am 4 for 5 - he is 0 for 5 - coincidence? luck?