Quote - I used 'hack' in the engineering sense, where it means cobbled together or a quick fix solution. Hacks are not wrong or bad, in fact they are often the only way to solve things sometimes, but they are not long term solutions. You should only rely on them till there is a better, more documented way. And I dunno whether BBs solution is incomplete or not, I don't know enough about how alt diffuse works to comment on that.

I don't have any documentation on Firefly's GC implementation.

I do, however, have Bagginsbill's documentation. It's all over the threads here. And it appears to be remarkably complete. So, based on your criteria for using a solution, I might stick with the "hack'.

Quote - Personally I would 'trust' render GC more and try and find what's going wrong in it...

...which is impossible to do without a full disclosure on how Firefly's render GC works.

Monterey/Mint21.x/Win10 - Blender3.x - PP11.3(cm) - Musescore3.6.2

Wir sind gewohnt, daß die Menschen verhöhnen was sie nicht verstehen
[it is clear that humans have contempt for that which they do not understand] 

Metaphor of Chooks