Left some 2k in mine and its kinda scrap now

So i'm looking around for a cheap usable replacement. What's the advantages/disadvantages between a suction and a gravity fed gun? Also, is there any extra gun requirements when using 2k? I never had any trouble running 2k through my old gun but as I know no better to compare with, it kinda makes sense to ask those in know

Also, noticed some dodgy looking electric guns??? These worth thinking about or are they in the same league as electric superchargers?
Cheers,
Stu.