Dom Wars, Generations, Island Wars, and Battle Zone mods do not need porting.. they were already v531 to begin with...
as for the other mods, such as Unity.. they are already working on porting over to v531
Several other Mods are porting.. Like Praxis is creating a mod and is in the process of building it for v531..
so many servers will be v531 soon and those running v500 servers will most probably upgrade to v531 as soon as their campaigns finish, if not sooner..
the v464 or out of box servers will still be running, but many of the v531 players will probably advertise v531 on thejm for the next couple of weeks pulling players across to v531...
so upgrading is up to you... however, many have already claimed that there is much improvement in v531.. so far very few bug reports have been posted, mostly dealing with a couple single player scripts...
so it is up to you..
Gl and HF