I wouldn't say you get better penetration... well, I guess you do but what Im getting at is if you have a welder big enough for the job then you don't need gas. Flux core wire is basically just a band aid for having a welder that is too small. For example, a Hobart 140 is rated for like 3/16" material with .030 wire using gas I think. With no gas and Flux core wire you can weld 5/16". I have a Hobart 210 (with gas obviously) and I love it. It is rated for 3/8 single pass with gas, and I have personally welded 1/2" (and even a little 3/4") and felt just fine with it, you could see it really burning in and melting everything nicely. My suggestion is to think about what you really need the machine to do and size it accordingly, then go buy the next size up. There is nothing worse than buying a welder and then 3 months later realizing its not big enough for what you need it for.