Wuestenfux has just screamed how bad stability of 6.3 is, then he I triedd a game with exact same people except for him and we played to the end. This experience I had myself in the 6.2 release, where I had one of the last prefinals which i though was the final from suddenstrike-maps.de .. in short, get the offocial version, dont use pre-final betas.
In short, no problem exists except that some people are abit too eager and use outdated betas.