How fast do you want a term sheet signed? You can of course say "we're not interested in becoming a DE C" and you'll lose 50% of your candidates and you can of course say "we've already set up the DE C" and you'll lose none of them. But if you say "we'll set up a DE C when we need to" you signal that you aren't confident that you'll get the round signed or that DE C is something you'll do begrudgingly, thus advantaging firms that can invest in Canada, so it leaves everyone scratching their heads.

Personally, my current company is staying 100% Canadian. The headaches dealing with the American tax system aren't worth it. If the revenue is there the capital isn't far behind, and I rather spend time optimizing the revenue of the company than getting slowed down with lawyers and tax attorneys plus I trust Canada's judicial system more than I do America's. Not by a lot, but still.

All this doesn't really matter if you're pre-product market fit or pre-monetization though. In that case it's almost always better to just set up the DE C because you have less leverage / allure.