The first thing to keep in mind is that in best case you will get what you pay for.
I would ask the manufacturer to send some closeup pictures of the machine construction. expecially about the surface finish at the rails.
I don't think any chinese companies build Taiwanese rails and screws etc into their machines unless they are asked to do that, then they may do it for extra cost,
but they often telling that even when they using Chinese parts. Nowadays you can't really distinguish between chinese and tiawaniese rails and screws, the only difference is often only the quality.
Chinese often even place hiwin marks on the rails, because they have the equipment to do the marking, they just don't have authorization from Hiwin and quality control by Hiwin.
It's hard to give you an answer if it will worth to buy a machine or not. The heavy weight is a good sign, but it is not the only thing, because weight put in the wrong places make a machine even worse then if it was light weight. high weight is usually good, but only if the design is good.