This frame being offered by Tantan is an unfortunate consequence of the high demand and interest in counterfeits. A few sellers, like Airwolf, have moved from open molds to mostly selling copies of other frames. I have no idea if these are better quality than other copies, but I doubt it. Afterall, where does the money spent go? Probably not into doing actual engineering work.
Don’t discard the possibility that big western brand stuck with too much inventory move their overstock through back channels rather than discount heavily under their name which would not be good for their high end and exclusive image…
LOL at them being overstock from a Western brand. This doesn't happen unless that Western brand sells a catalog frame. It does happen for open molds or for molds where someone has bought exclusivity for several years but doesn't own the design. That is not the case for Cervelo, Specialized, Factor, and Pinarello, which are also not using these factories.
There are also visible differences between this frame and legit SL8 if you look close enough.
