As a compromise, you could add these new features to the premium membership. Add user agent detection and format the screens so they look good on a typical Android (800 x 480) screen. The newest iPhones are even higher resolution (960 x 640) so if you target Android screens, you'll look good on iPhone too.
Right now, DGCR isn't all that usable on phones, requiring lots of side-to-side scrolling and pinch-to-zoom. So putting in the effort to format the new stuff for mobile should get you more premium members. And there would be no developer to pay -- you get to write all that yourself.
Granted, this won't work if you're playing in the Kalahari Desert and there are no cell towers in range. But with HTML 5 providing a local storage option, you could consider a DGCR "offline" mode that would save scores in the browser and upload when you do have connectivity again. Not sure which browsers support that yet, but it's coming.