There is a general limit of $35,000 for Pay Over Time. It does not correspond to your internal spending limit in any way. This limit has been around for awhile and Amex hasn't reported the Pay Over Time limit in the past, so I don't think so.
FICOs (2/24/12): EX 752, EQ 740
Chase Sapphire Preferred, Freedom; American Express PR Gold, Blue Cash Everyday
