Just a data point that might interest people here:
Booked a OW Spirit flight on the portal for my family, total was ~$267. Same flight was available on Spirit.com that day for $204 total and Cap1 has a price guarantee, so we called and got credited the ~$63 difference. But today we got our travel credit for $267, not $204. So if you find a price guarantee situation, you can sort of double dip a litte.