Yes, definitely buy it. There might be some problems or bugs still, but considering that those games have no native OVR support, it’s really awesome.
I just contacted support to receive a new key (after Windows installation changed again), and got answer within 6 minutes, at 2 AM on a sunday night.
After spending 350 Euros for a development kit (actually i bought DK1 and DK2), paying those 30 additional bucks is a no-brainer for me.