I wouldn't say they'll get stunted from breeding, but the females will definitely slow down to a near halt from it. Males aren't as heavily affected, and in some cases it can actually cause them to get growth spurts from the hormones they start to get due to instincts kicking in.
Just my two cents. I've never personally bred festae, I've read into it a lot - but pretty much squashed the option when I found that A. They're very hard to find out here in California and B. You need a huge tank to breed them in. Even moreso than other cichlids, because adult males are known for snapping on the females.
Similar to what you see in midas, they're just wife beaters.
It is common in all young cichlids for the females to be in charge, so having females kill males when they're only at pre-adult size is understandable. If you've bred a lot of cichlids you'll notice that, while females have it down pat most of the time from the first spawn, males often don't have a clue as to what they're doing until the 5th or 6th spawn.
This is especially so in South American cichlids, in my experience.