hmm, have used old tippie 98's without feed problems with a grav hopper, but i wouldent say there was any harm in getting one, just that youd be better spending cash on better marker, tippies are good starter but 98 is standerd site marker.
+, you know you have shot in chamber, you can realy fill up your hopper and not worry about miss feeds
-, cost, may not realisticly do that much for your game