I don't really pay attention to the fare types. Overall, I would say I find a 5-10% discount about 70% of the time, which is not often.
Sometimes the price is the same.
Rarely the price is higher (in my experience, when doing multi-city, you can get better discounts on AA since amex prices it weirdly)

Bought a trip at a 25% discount from the going price yesterday, PHL-MIA with 2 stops (trying to get those segments up + I like flying), N Fare.

I use my Biz Plat with AA as my selected airline, pay with amex MR, then get a 30% point refund = cashing out my MR at 1.53 cpp