The above advice is solid; here is a few other points from an insider's perspective to consider:
-based on your overall academic profile, you should not have any major issues landing FM (not necessarily at a top academic site though) in the US through Jag within the near future -- barring major adverse life events or personality flaws that would hinder you during rotations/interviews. The SoN changes will likely become a somewhat bigger issue going forward not just for residency but also fellowship training as Health Canada tries to manage healthcare expenditure. The problem is not just forecasts of decreasing SoNs for the future, but also the increasing number of Canadians studying abroad trying to snag one after matching in the States. The caps for FM and IM were not breached this year. As mentioned above, FM's high cap will provide a better buffer compared to e.g. Rads despite the different match rates.
-Dividing CMSPA numbers by four to evaluate Jag's stats is not the best approach: Jag takes far fewer students than other Polish schools (Warsaw, Poznan, Lublin, Silesia, etc.): a max of 40 people a year in the 4 year program; matriculating class sizes are usually in the low to mid 30's. Attrition/blockage is not near Caribbean (30-50%) rates, but since being approved for US DoE loans this year (=> the need to keep up USMLE pass rates >75%) the administration has signalled that they will be more strict about barring under-performing students from taking the Step without decent compNBME scores. I would guess 20-25% overall attrition+block going forward for the 4 year program. Moreover, the residency placement lists that you have seen in this thread or on the school website are not off the mark: traditionally, about half of the graduating class has ended up with a residency in the US/Canada, and another 20% get one in England/Poland/rest of Europe. The school does not provide miracles, but they do have linkages to select residency programs, helpful alumni/graduating classes, and a decent reputation with programs in the US. YMMV, of course
-If you are set on FM in the US, then financial compensation is not at the top of your selection criteria, but you still need to consider the difference in training length as well as the tuition/CoA between the two options -- MSUCOM is, btw, uniquely unaffordable for out of state apps. Theoretically speaking, waiting another round for acceptance into a Canadian school and then jumping through hoops to get accredited in the States will mean somewhat of an overall financial hit compared to the immediate Polish route, but if you are this close to getting in at home, I would stay put and try again: as mentioned by Commons, you might discover a burning passion for another speciality later down the road; an IMG's chances for non-primary care matches in the US are not close to those of a CMG's at home/US. Also, I assume that you know the difference in practising FM in Canada vs. in the US, so I won't get on a high horse on that topic.... Btw, the 12 week rule for rotations is generally applicable (there are a lot of exceptions and twists to this) to those who are aiming to match in NY state; otherwise, you may ignore the rule -- and many do since NY state IMG residency spots are often filled in by linked Caribbean grads. Gluck.