Chris:
I looked up what the VSR90 is, and it works just like my Badger 150's and 200's except that it is gravity feed, mine are suction feed. A gravity feed type requires the least pressure of all airbrushes, and can work with very thin paints and fine lines. It is a very nice airbrush. You probably do need to get a regulator for it, though, before you can control the airflow well enough. I set the airflow with the regulator, depress the button all the way, listen to the air, and then pull back on the lever untill I have the right amount of paint flow. I'm not coordinated enough to manage both down pressure and back pressure at the same time. Too much like rubbing my tummy and patting my head at the same time. Never could do that either.
Here's a link to the kind of regulator that works, this is a Paasche brand but the brand isn't important so long as the in and out fittings are adaptable.
http://order.icorp.net/mpr/mo?review+c_dixie+q_1+i_99R75+n_Paasche_Regulator_Gauge_Moisture_Trap+u_33.20