3000 or 4500 has no direct effect to the gun, all that does is tells you how high the tank needs to be filled (so find out what your field fills to and pick from that), if they fill to 4500, then get it. 4500 means more shots per fill than 3000.
There really seems to be no necessities for the Omen, just a tank, a hopper, a batt., and some paint.
The less paint wasted, the better the marker's operator...
$161/450 'nother BKO fund..