Well I have the 056 and very much like it. I weigh 230 lbs all geared up and no issues whatsoever riding at least once a week for almost 2 years now. The frame has proven itself.
That said, if I were to buy a Chiner hardtail today, I'd probably go with 041 as it's a bit lighter and the only thing I don't like about my 056 are the lines of the frame. Imo, it's not the most aesthetic of the frames and the alternatives look better to my eye. Of course, that's subjective. There's also the 256 and 106 that are worth looking into. But if you find a good price on the 056, I wouldn't hesitate to get it, it's a great frame.
And to answer your question, most of the frames sold by the various manufacturers are basically the same frame. Don't worry about that too much, just find a a consistent and honest seller. Peter from xmcarbonspeed.com and Bert from xmiplay.com are worth checking into to see what they have in stock. Between the two of them you should be able to find what you want in stock.
As far as transferring parts form your Marlin, just make sure you do plenty of research so that everything's compatible with your new frame. Sounds like your in the initial stages of research so
just be sure to do your due diligence as far as research to avoid any issues.
Welcome to the forums.