Ehh, I don’t know. There’s a difference between an organized GB with a domestic party and what the CN vendors call a GB, which is a pitiful attempt at a promo.
Like I said in a previous comment, some of them are run very well, but any of them can go sideways…just like your direct buys from CN can go sideways. Keep using whichever method meets your personal risk tolerance and don’t spend any more with any one source than you’re comfortable losing.
Personally, I like the ease of 3P testing, the better prices, and not having to have a package with my name on it go through customs, so I’ll keep doing selective GBs. (And again, I’m not talking about what the overseas vendors refer to as GBs.).