Try it out, but Fluxcore is definitely a different beast. I would not trust my life (or anyone else's) without TONS of practice. I see a lot of guys here with some ###### welding skills riding around, but myself, I personally bought a Hobart 210 MVP, practiced a metric-shit-ton with just flux core (just now gas), and am now just getting around to starting on my bike.
Practice, practice, and practice some more. Join some forums, or better yet, get someone qualified to teach you and inspect your welds (if you're doing your subframe).
My personal opinion is save up and buy a decent welder with the option for Gas down the road. Trust me, you'll wish you had once you get the bug. Don't buy a bottle unless you have no option to lease it. I pay $40/yr lease and $35 per exchange on a 80cu ft cylinder. 80cu ft will go a loooooooooooong way in welding.