Hi Connor,
First, concratulations with your choice
Whenn you buy a Palmcontrol you have the choice to buy a beautiful burl wooden handle for it. Just for the looks.
The santoprene handle is the standard handle that comes with the PC.
The steel handle or damascus one are increasing the impact of your piston. The damascus one is also because its beautifull ofcourse.
So, you could get a stainles handle extra to increase your impact.
If you like beatufull tools and you are not limited by budget, get the burlwooden handle and the damascus one
The NitroG20 is a large bore airgraver made for heavy duty stuff like motorcycle engraving and such. So it will depend on what you want to do with your tool.
Hope this helps,
Daniel