I'm not a huge fan of side mounts personally, or side holes in general.
Not only do they mess up the path of your airflow, but usually they're unfiltered so you end up getting a ton of dust inside the case. They do cool well, obviously, but it's just not worth the effort in my opinion. A good few fans in the front, top, and back should be more than sufficient. Plus, removing the side panel they're on is a pain in the arse having to unplug them every time.
I suppose you could get around this by setting them up as exhaust, but not only would that look super ugly from the outside, it would also be a bit pointless since heat rises, top fans exist for a reason.
Each to their own I guess, but I replaced the window on my C70 to a blank...