There is no reason you cannot use the same database for both the app and the forum. I won't make another account, so looks like I am abandoning the app for now and using the device.
If you had the same user for the app as you did for the forums, you could do rewards/badges (for length of cooks, number of cooks, types of recipes) easily through API calls to whoever hosts your forum (Vanilla is my favorite). Then your marketing could have all of the fun with all of the analytics you would be collecting.
Any who, I am eagerly awaiting the fix for this 'two separate accounts for the same device that aren't connected' issue.