I still see the DDE card as a substantial savings. You also get free valet parking for your meals with the card ($10 a pop there), you gget a few other perks and discounts as well as getting a discount at an occasional CS location where you pay no tip.
The DDE card discount breaks down like this...
The DDE Card charges an auto gratuity regardless of your party size.
Party of 2 with DDE
$100 - Food Bill
$20 - DDE Discount
$18 - Auto Gratuity 18%
$5.20 - Tax
$103.20 - Total Bill
Party of 2 without DDE tipping 15%
$100 - Food Bill
$15 - Discretionary Gratuity 15%
$6.50 - Tax
$121.50 - Total Bill
Also, if you're a party of 6 you'll be charged an auto gratuity regardless of how you're paying BUT you will not be charged two gratuities. I'll break it down with and without DDE below for you so you can see it
Party of 6 with DDE
$300 - Food Bill
$60 - Discount
$54 - Auto Gratuity 18%
$15.60 - Tax
$309.60 - Total Bill
Party of 6 without DDE
$300 - Food Bill
$54 - Auto Gratuity 18%
$19.50 - Tax
$373.50 - Total Bill
You'll notice that the tax is less on bills with the DDE, that's because you are taxed on the food bill post discount. The tips are the same because you are tipping on the food bill pre-discount.