I just tried the new feature to copy the texture colour into vertex colours, and my original plan was to try and see if I could use it as a work around to use vertex-alpha in hairstyles as I don't know of any programs I could paint it with. For that purpose I created a simple subdivided plain that I applied a very crude texture to, with DXT1 alpha as a simple transparent circle in its center amid a black non-transparent rectangle. But using the "copy colours from texture" feature only left the entire plain black, and when copy pasted the vertex colours onto a duplicate it was plain black as well.
So I wondered whether I just overlooked something or used the wrong approach, or whether vertex-alpha is not affected by this feature after all. If it is not, maybe somebody could recommend me another way? It just feels so wrong to use beard and hairstyles without vertex transparency since I found out about it^^
And although I suspect I already wrote it somewhere I want to thank once again for the possibilities openBRF grants us late edit:
After testing around some more and even trying around with ply formatting I found that it must have shown wrong in game because I used a shader that doesn't support vertex alpha. Obviously the preview in openBRF doesn't show the vertex alpha either so that was a bit misleading too maybe, but if applied to a mesh with the proper material and shader it seems to work fine now.