2 tubes take up less space than one of those magazines. When I'm about to run low on paint, I have the next tube in hand. I can reload a tube with a gate faster than that mag can be extracted, rotated and reinserted, I'd wager. That's why I never could justify a mag gun, no matter how hard I tried. The mags are just inferior to 10 rd tubes in weight, bulk and simplicity.
Wouldn't you really rather have a Buick?