That's weird... I've been running 1 card mining DRK for about a month and will give this a try... How much DRK are you pulling in with that setup, if you don't mind me asking?
I'm currently running some tests between P2Pool vs WafflePool vs Single Pool DRK mining.
Ballpark for all 3, depending on difficulty of course, has fluctuated between 10-20 DRK per day.
At the moment, WafflePool then buying DRK is just edging out P2Pool which is just edging out Direct Pool mining DRK.
The additional DRK I'm accumulating from going down the WafflePool approach is not sufficient for me to ignore that P2Pool would be the better long term solution for the network, so unless something amazing happens on WafflePool over the next few days, (I'm giving each one 1 week), I will be settling on P2Pool.