Well, I voted both, since I'd rather have both, but since I usually only have the option for one deck gun installed, I allways put it on the stern. It just seems more 'sporting' that way, and it gives pursuing destroyers something else to think about besides catching me.
And I swear I get better gas(battery) milage by not having to push a bow mounted deck gun through the water. Kinda like having the tail gate down on my truck, only different.. :p