There's nothing on the RCS Phantom holster that will prevent you from getting a full combat grip before drawing the pistol. The sweat shield is very minimalist. Just enough kydex to do the job, and none to get in the way of manipulating the gun. As you can see, the holster is like a second skin around the gun. And the kydex is very thin... and doesn't add any bulk at all. You can't ask for much more if you're looking for a concealable OWB holster.
Here are some quick and dirty photos with my G19 for your viewing pleasure
Note: The standard belt attachments that the holster comes with are very good. They keep the gun nice and close to the body. However, I opted for the pancake belt attachments shown below as they pull the gun in even tighter.