Only you can decide for your system. Keep in mind, you're also (probably) running 7.2k SATA drives... the Supermicro chassis are built for 15K SAS stuff. I can assure you they generate substantially more heat.
We were having some discussions on this in another thread, but I'll add them here as well. I have a CSE847 36-bay chassis, with 14 15K drives, 6 7.2K drives, and 4 SSDs currently installed. After some poking around, I found that the fan connectors on the backplane never seem to idle back at all, where the motherboard connectors do. So, I connected three of the fans connected to the backplane to the motherboard (ran out of headers) and left the 4th disconnected. I then loaded all of the drives heavily (2 threads of dd from /dev/urandom to each drive, simultaneously) and let the drives get hot and heat-soaked. I then pushed the fans up to full speed via ipmitool and let that run for an hour. I found a 2C difference in temperatures. This tells me that, at least in my configuration, the chassis are "over-fanned".
I also added active (fan-based) heatsinks to both CPUs, to help extract that heat from the system. With all of the these changes, the system makes a constant low fan noise, rather than the normal screaming-banshee behavior.
Now, if I had 36 15K drives, a pair of E5-2687W v2 fire-breather CPUs, and every PCIe slot full of high-end graphics adapters, I doubt I would find the system to have more fan than it needs. Supermicro builds these systems to cool themselves properly at full load... so, you can cut back some, but you have to do your own research and monitor your own temperatures to make sure you don't cook something.