Yea, it seems as tho AMEX and Delta AMEX are giving out courtesy credits more easily, although I'm sure you can't dip too often.
But, for example, a few months ago I cancelle both of our Delta AMEX Platinum cards. I already had a regular AMEX Platinum too and I wanted my husband to have it.
Then I changed my mind and decided that we could get along without him having an AMEX card altogether.
When I called to cancel the AMEX Platinum, the agent worked hard to keep us. He offered a $150 courtesy credit if I took an AMEX gold for my husband... with the miles still accruing in my primary account.
In addition I told him that the reason I'd previously cancelled the Delta AMEX was because of the giant increase in award miles required for US-Europe sky-choice business class seats, and that I wanted more flexibility with my miles (hotels, etc.)
He then told me (and this is the important part) that on a one-time basis, he had the authority to offer a sky-choice domestic flight for sky-saver miles. I'm sure that could mean more than one ticket being booked at the same time. The key being that he told me that if I decided I wanted that option, all I had to do was call back and reinstate my Delta AMEX cards.
Next story: Yesterday my sister was heading out on a business trip and her new AMEX Platinum card had not arrived, even 'tho it was supposed to have arrived a week ago. She wanted to use the DL Crown Room and was annoyed because she didn't have the access (nor a membership). She called AMEX to complain and to also ask that they overnight her the card so she could use the crown room on her return flights.
Well, AMEX gave her $100 credit to her account so she would be able to go to the crown room and buy herself a day pass for each of her flights. That will leave her with a $50 courtesy amount after the costs of the crown room.
(Oh, and yes, they are also going to get that card to her via Fedex).
So tell them you're thinking of leaving them, since there are other mileage cards that interest you. And see what they do.
Good luck,
Rita