Range rental guns are often poorly maintained, and often the ammo they give you to use is pretty poor quality.
Of the problems I've heard of with the G30, sometimes they'll fail to feed with certain JHP's and not others. Most G30's don't have that problem though. And the only other problem, as with any Glock, is that there's a small chance of getting an out-of-spec extractor that doesn't move freely enough which can lead to feeding and ejection problems.
With the G30SF, there were a good number of people who experienced a failure to return to battery problem where part of the trigger bar was rubbing on the slide, and in some cases even the ejector was rubbing on the bottom of the slide. I've seen two G21SF's that had this problem as well. It's thought that the cause is the rear frame rails being mounted too low in the frame. In some cases people sent the gun back to Glock and it was replaced with a new one, in other cases the latest 4256-1- trigger bar fixed the problem. Some people polished the point on the trigger bar that was rubbing on the slide until the rub mark stopped appearing after a range session, and the problem was fixed. The characteristic symptom of this problem, whether the gun is loaded or unloaded, is that when the trigger is held to the rear and the slide is cycled, the slide will hesitate or fail to return fully forward.
Here's the area where the rub mark may appear: