The DFC head and helical gears have nothing to do with each other. The ONLY reason to run a helical gear is if you are putting a lot of torque to the head from teh motor. The pitch of the gears is a bit larger, giving it the ability to handle more power. They are slightly quieter though which is the reason I run them. But with a motor that is pulling 640 watts, I sorta needed them lol.
If you have straight cut gears, run them. As a new pilot, I doubt you will be laying the power to the gear like a smack 3D pilot would. But, if you just want to run them, it won't hurt anything.