I have both. Win-win.
I'm damn near full Rampage and can wipe out an area by myself. A ton of fun, and your ammo costs are lower once you get the cooldown low.
All of my other points are going into Gun Lust. As it stands down, 7/5 points in Health regen for the Brawn tree, and that's it (class mod, otherwise it's just 3). It's a bit rough until you have great guns, and then life is beautiful.
Also, I picked up a Purple corrosive pistol, great damage, but there's a caption called "Dodge This"--I then realized that it teleports bullets to a target as long as you aim and fire properly.
I love this game.