Amex FR Scare is probably because of inconsistent usage where there is a lull and there is a spike and from my knowledge it happens to users who have Business Credit Cards and not because of your credit worthiness.
IMHO, I would not let that stop me from applying for a Barclay's card as they usually pull TU. Although AMEX might look at your credit report and might decide your a churner..lol which we all are