The results are not surprising given the nature of the participants in the survey. I look at my own situation and it is pretty similar to what you report: 4 cards, no balances, Amex Blue & Citibank reward cards - used wherever credit cards are accepted to increase the cash back. I never actually checked my credit score - I can’t bring myself to pay for the privilege - but I check our credit reports every 6 months or so to make sure all is well (it is). Since we have never missed a payment on anything (except for a couple of 2 or 3 day delays when we forgot to make a payment), I expect the score is at least decent.

Good job on the detailed report.