Preface Statement: I've never been nor will I most likely ever be able to "comfortably" afford the honors of hunting in Canada.
That said, let me say this towards this post;
As someone who is not a Canadian resident, who would have to travel 2,000 miles and who would have to put a very sizable amount of funds together in order to go, I have a very skewed view on this subject.
I have hunted deer for 30 years. Have killed them with everything from 22 cal to 50 cal, bows to buckshot. I own a variety of deer hunting rifles that range from flat, fast rounds to bulky, lumps of lead.
Should one day I be blessed enough to go, you all can rest assured I'm taking a rifle in which I'm extremely familiar with and "ONE THAT CAN PENETRATE FAR ENOUGH TO GET THE JOB DONE EVEN WHEN THE MOST IMPERFECT SHOT ANGLE IS ALL I'M ABLE TO TAKE."
That's not to say I will take a "Texas Heart Shot" (I'm not taking any none lethal attempt) but an extremely harsh qtr'ing shot on what might be the most expensive trip I'll ever take in my life, on what would most likely be the largest deer I'd ever have the chance of killing - I want to know I'm putting enough lead on target with enough energy to get the job done with as minimal of a failure rate as possible.
Does that mean that if I were there, handed a 243 with basic rounds that I thought I couldn't make it work with getting a good shot off? No. I have no issues with my shooting ability or the ability to poke a vent hole through a game animal to bring it down.
But this is a $5 to $8k trip for me, 2000 miles from home, once in a lifetime sorta thing; that said - give me a very familiar rifle, one I'm able to shoot accurately in the field, with a proven load ample enough to penetrate despite what conditions I'm afforded. Sometimes, good enough isn't good enough when 16% of your annual income is on the line for a deer.
If that particular rifle is a 308 Win, then that's exactly what you should load up. If it happens to be a 338 Win Mag, then congrats on having more medicine capable of doing the job when everything isn't seeming to add up. It's all about putting your bullet on target in the right place, but sometimes that means it has to travel through a whole lot of meat and bone to get to said "vitals."
Just saying "USE ENOUGH GUN" isn't really my take... If I can't shoot it accurately then it's useless. But to think that I'd take one of my smaller calibers even though I'm 100% familiar with it and trust it is absurd when I have larger, better penetrating rounds that I shoot every bit as proficient.
