i play neogeo cd a lot, and Retroarch FBneo play them really well.
but most of the time i just use Rain32 for 2 principale reasons :
01 - Loadings : in rain32 you can up the cd speed to x48 making the loading virtually instantly. that's not such a big deal on retroarch if you have a turbo button assigned to your controller you can speed it up (and sometimes you just want to watch the loading screens because of the artworks or nice little gifs XD )
02 - my principale reason is this; in retroarch the music stop at each loading and reset, let me explain:
let's say you are playing Kof for example versus the psych soldier team, they have one theme wish is athena song for each round the song will start... and when you finish that round the music stop... and start again in the next roun.
while on Rain32 you have an option to make the music continuous
but tbh Rain32 has some glitches in some games (i'm aware of Art of fighting 2 and Breakers ) while FBneo doesnt ! with some luck FBneo is going to get the music feature!
all this said i didnt try this new core and will do right away !