I don't have any specific results to show you, but I tried it with 2 fans, and 4 fans, both as intake and exhaust from my case and the 4 fan setup didn't make much of a difference, maybe a degree or two. Also exhaust works a few degrees better then intake, just make sure you also have some fans acting as intake at the front and side of your case
yeah i had a feeling its not worth buying 4x fans on it.
i have hafx case and i only got 2fans on my h100 set to blow air vertically upwards direction. My hafx case has another fan there thats already set to exhaust, so that would already help with a push pull effect anyways.
i think 4x fans is just going way overboard.