How AMEX affects total credit available

[Doomed]

Hi, all.

Please forgive me if this answer already exists someplace in these forums.  I've searched and searched and mostly only found all of you wanting to know how to get an AMEX.  

Anyway, does anyone know how a non-revolving AMEX factors into a person's total credit available and, therefore, the credit used vs. total credit ratio?  For what it's worth (and I don't know if this adds anything to my questions ), but I went from a $1,200 balance on my AMEX a couple of months ago to a $3,200 balance this past month and a recent credit alert on myFICO showed that my FICO dropped from 724 to 723.  One point drop for an additional $2,000 of credit used (that I will, of course, pay off in full). 

So that begs the question: what's more valuable to a person's credit score, a no preset spending limit AMEX or a credit card with a credit limit of, say, $15k?

Thanks!

-Doomed

[llecs]

Non-revolving Amexes (or Amexs?) are scored differently from other non-charge cards. Most FICO versions, including the EQ FICO on here, ignore the balance and "high balance" for utilization purposes. All newer FICO versions are the same, including the verisons used by a vast majority of mortgage lenders. The reason it is ignored because you have to PIF monthly. Scoring aside, my mortgage lender ignored all charge card balances when looking at DTI. However, the older TU98 FICO version on here does factor in the balance and high balance and uses that to factor it into util. 

If you got an alert, then the only myFICO product that offers an alert on balance changes is SW. So, if SW provided an alert for a balance increase on your Amex (e.g. Green, Gold, Plat) then the score drop would not be due to any util change. FICO will score the balance. The one point loss could be caused by multiple things outside of the Amex, and including the Amex. SW provides a net score change and th epoint change could be factoring in multiple changes across all accounts. If you have a 1 pt loss, then it could be due to adding a balance on an existing card from $0 to $whatever.