There is another pair of coins that was quite a different but somewhat similar scenario. Anyway, the original plan was for them to create a new coin and exchange for the current holders of their existing coin. For whatever reason they chose to create the new coin and keep both coins which resulted in the first coin being basically worth nothing. This is not to say that it will change in the future, but as of this moment, I am a bagholder of the original coins. With that stated, the devs and the team of the said coin are good people, with a good "mission" but in my opinion their "vision" was flawed and not well thought out.
Speaking as a Top 20 holder of FIBRE,
SB_
Yin/Yang tried to switch to Harmony - it was a disaster. But those guys weren't nearly as developed or communicative as the Fibre devs. So while I see the similarity, I don't think that the instance is analogous. Still worthy of note though...
I'm not familiar with Yin/Yang but rather am referring to BST/BSTY. If it were my decision I'd focus on Fibre, continue to do good things, create an elite community and not look back. As mentioned before, build value in Fibre as it currently exists and the money that is required to fund things like BlockCypher will come...