Think about it this way: Will the user "lose their place" on your page if they click a link and go back? Will the user lose any filtering or search options? If the answer is yes to either, open in a new tab. I personally make this determination all the time, especially on social media after I've scrolled a lot and don't want my "progress" to be lost.
Opening in a new tab has become some kind of standard UX. Regardless of that, for this kind of site it would be very useful for product spec comparison.
I think not forcing links to open in a new tab is the right call.
However, the point about losing one's place is a valid one, and I agree with the other commenter that said it would be good to encode the state in the URL to solve that.