One point I'll disagree with is the viability of s SRED. It's a documentation nightmare and hiring a consultant to file for you is basically mandatory - they take 25% of your return. IMO, not worth the distraction in general, and definitely not if you're questionably eligible due to u.s. status cofounder.
Canadian banks, even with USD accounts, are handicapped. ACH for example, is a non existent term at Canadian banks.
Canadian customers are fine paying USD, if your business is USD based. All your expenses/providers will be, so it only makes sense to bill in USD.
Nexus is a serious issue. Hire an accountant who is familiar with this. I learned for example, that _where your website is hosted_ is factored into the decision. You can claim to be Canadian, but offering services/downloads to u.s. customers served from a u.s. server counts as 100% u.s. As mentioned above, % of sales is another big factor. If you trip 51% (and you will, Canada is too small a market), you risk being assessed.
Incorporating and filing taxes will work out roughly the same in either country. I'd need the recommendation to incorporate in Delaware, and just file as a u.s. company.