I performed lots of testing against the rockbear for this, but consistently the ranged damage is outdone by melee. An example of this is that gun pp Regen is 70% ranged attack while melee is 200% melee attack.
I'm sure most people who run gunblade aren't making a gun build, but if you recall the gunblade class in JP was advertised. And the presenter stated we should be building ranged attack(along with the character being shown is using ranged attack at 5k while melee is 3.5k)
I'm waiting on the actual tree to show up before fully converting, but it somewhat makes me sad that I went through all the numbers, scaling, and found that the base gunblade is so borked to one side.