I was talking to "R". It seems that they hold the amount of charges (not interest, not BT) as a BIG factor in what you qualify for, (BT,base rate). the guy said every charge you make, they get a cut, so they like to see people who move alot of money through their accounts to get the best balance transfer offers (with reduce their profit) and lowest base APR. makes sense
I've had the plat. select card for almost two years. I've used it only for BTs and never charged a purchase on it. I called a few days ago and got the purchase APR reduced from 11.9 to 6.65.