What kind of spend per year are we talking? I ask because I face a similar dilemma. Although I have the Club card which doesn't give 1.4 only on 25K spend. After 5 months and 42K spend, I'm at 63K M+ miles (total spend only as some of it is UA-based which is 2x). If I charged that on the Explorer, it would be 52K if my math is right. That doesn't make up for the huge difference in the annual fee but over the next 7 months, I'm hopeful that I'll realize enough for it to be worth it.

The fly in the ointment is the Freedom Unlimited which is 1.5x UR for a $0 annual fee card provided I have the CSP. This destroys the Club card in almost every way except benefits and UA spend. I now have 8 months to see if I'll stay with this course or come up with a mishmash of others cards to accomplish a similar outcome.