From experience, they have virtually the same results in my testing. I have owned a G2+, Gold Bug Pro and 2 F19s. They could all run at 99 in discrimination mode, and hit 8" coin sized targets, with the same coil. If you are looking for extreme raw depth in discrimination mode you have the wrong detector. In all metal mode I found that the key to more depth was in coil selection. All four had almost the same air test and depth results using the 11x7" stock DD coil, the 10 x 5" elliptical coil and the 5" round coil which were barely deeper than the diameter of the coil. Using a Detech Ultimate coil (13") really changed things and gave all of them the depth (11" plus on coin sized targets) I was looking for and did not have a bad effect on separation, target ID or weight.
So, instead of upgrading (moving sideways in my opinion) to the G2+, I would get a Detech Ultimate coil and see how you like it.
Jeff