Do Rednose Pitbull's Get Aggressive During Heat?

They can get more aggressive for sure, any dog can. The concern there if it's a bit extreme would be a problem with your dogs hormone levels which could be a BIG problem (health) aside from and in addition to the aggression.
They are also healthier and live longer with fewer risks when fixed and pit's and pit mixes are the number one dog in the shelter's and rescues right now whether it be accidental or on purpose and get put down in the millions :-(. You also risk your dogs life any time you breed as complications are common. You also may lose some of the things that made them such great pets in the first place. They become 'breeder's'. More aggressive, more likely to run away or escape, and they mark now  (NOT just males). All around the reasons to spay and neuter far outweigh any reason to breed on purpose or to risk an accident. It is definantly something to consider very carefully and the risks to your pet by not fixing them or breeding shouldn't be the least of them. Here's some information for you. :-)

www.irvinevetservices.com
www.amstaff.org
www.pbrc.net
www.woodhavenlabs.com
www.wildheirlabradorrescue.org
www.dogplay.com
www.learntobreed.com
www.geocities.com
www.dogfoodanalysis.com