They do in-fact allow business and personal card totals to be combined for qualification though I am not sure if there is a rule regarding how much percentage from each may be required. My biz card spending was only 5% of what it took to qualify...
Also, I am unaware of anyone actually reporting that the $250k rule was "relaxed" for them and they were allowed to get a Centurion with less than $250k charged and paid. In fact, when I applied for mine I was at $248k and change charged and paid. The agent told me to either wait till next month or send in a check for the couple thousand right away and charge anything for that amount. Once the check was posted to the account and I charged the difference I could call her directly and she would process the card for me.
P.S. Try a search. There are only 1500 or so threads on this...