Hi,
It is true,right or left the only impact in your SEO could be if it gives a bad user experience and increases the bounce rate. Maybe choose wisely the links in the nav bar so they are not to many and they actually point to webpages you want to get link juice to.
In theory when someone looks at a website tends to check more the left side, specially top left. check for website heat map on google.
What needs to be more visible, the navigation bar or the content? ... depends.
I don´t think that the great majority of customers will even realize that other pages in the niche have the sidebar on the other side. That is just because you are highly involved with your website and the niche and therefore even realize that.
In other words just a mater of design.
My personal opinion, I like right side navigation, looks more modern.
Sebastian