I personally don't know if there is a definite line in the sand for defining a running QB. However, within the context of this thread, I thought it was agreed upon that Cunningham and Vick were the definition of "running QBs" so because of that, I would think a reasonable definition would be to look at their pass attempt/run attempt ratio and use that as a possible numerical basis of defining a running QB. Following that logic, anyone falling below their ratios would definitely fall into the "running QB" category. Is my logic flawed?
The numbers I posted above indicate that RG3 rushes more as a percentage of his plays than Vick and Cunningham. Yes, I absolutely know that 7 games may not be a statistically significant sample size, but at this stage, it is all we have to go on and his stats may develop in such a way down the road to completely invalidate my argument. If so, that's fine and I even admitted that might happen.
I have at least shown that based on current stats, RG3's play distribution (him running vs. passing) is far closer to Vick's distribution than Steve Young's distribution. Furthermore, while I know that as a QB gets older his rushing attempts will drop, RG3 is on pace to exceed the TOP rushing seasons (in terms of attempts) of the prototype rushing QBs even in their younger days.
IMO, based on my quick data, RG3 needs to move his ratio from about 3 to at least Steve Young's level (5.75 IIRC) if for no other reason than to increase his survivability. I don't think he'll ever be a pure pocket passer (my example was Peyton Manning, whose current ratio is 21) or even get close to the ratio of Luck (12.5) and remember, Luck currently leads the AFC in QB rushing yards.