I would just not bother watching footage or an actual comparison in your case. There's really no benefit. I'm in the same situation as you and while watching random footage from E3 on Wii U, it looks fine. Sure there's fog, and the colours (for whatever reason) are somewhat different but I don't think it's a drastic difference.

I'm just hoping Wii U doesn't have more framerate problems since the Switch has some already. I wonder if any review will try to point out the differences or just not bother.