The G models are not "better" than the Elite models. The standard G models are simply a 9xFS with a decocker only, instead of the decocker/safety.
The rest of the firearm is identical.
The Elite series which is available to the public have additional enhancements to the 9x series. Such as front and rear checkered grip, forward cocking serrations, novak sights, 4.7" barrel with a deep recessed muzzle crown, no langyard, skeletonized hammer, extended magazine rubber base pads, hex head grip screws, D model hammer spring to reduce the trigger weight, slightly smaller grip to trigger length (aprox. 1mm) which has now been done to all the 9x line, stainless slide and barrel on a brut. frame. These are just off the top of my head. I'm sure there are more suttle changes.
This is for the Elite II model, since the Elite I has been discontinued. The elite series is only available in the "g" config. It can be had in either 9mm or 40s&w.
The G model is desirable for those who do not want an external safety, simply the heavy DA trigger pull to keep the weapon "safe."
I couldn't give you an accurate figure for the police trade in values, so I won't try to guess.
-Steve