Were you able to install the signed APK outright just like the unsigned on your phone? A lot of people have trouble with this judging by the online posts. I'm assuming when you sent the game to review sites, you sent them the signed APK?
Yes I'm able to install the signed apk. If there is already the same app installed with a diffrent key (or no key), then remove it first.
For Google Play, always upload a signed one. As far as I know you cannot upload a debug or unsigned apk at all.
Regards
Andy