Gan have recently announced that they are now looking for testers to try the new Gan 4x4, I have obviously applied for this but maybe you can too? Although I suspect they will be quite strict on who they allow, so you'd better be fast at 4x4 or have a big audience to stand a chance.
Regardless, this shows that Gan is very serious about ensuring their 4x4 is good, Matty Hiroto Inaba seems to be the only top cuber that is talking about the Gan 4x4 but he assures us that other Gan sponsored cubers such as Tymon Kolasinski also have prototypes so it is a bit concerning if they aren't using them.
Gan did release a 4x4 in 2018 but it was terrible, I never stocked it and it dented Gan's reputation considerably, Gan know that if they release another bad 4x4 then their reputation will be seriously damaged. Gan released a very good 5x5 last year which some top cubers use so we would generally assume that they would soon release a 4x4 but they have to ensure it is as good as it can be first.
