Quick data point...I applied for the Business CSR about a week ago. I followed up today to check on status. They basically said that even though I don't carry a balance, they had massive credit exposure across my personal and business cards. I readily agreed to lower the credit limit on some of the other cards to liberate room under their self-imposed total exposure threshold and received the approval email about an hour later.

A bit annoyed that I can't take advantage of the pre-June 30th semi-annual bonuses, but I'll get over it. Such a tease that they share the last four digits but nothing more.