Imo Splitting players to two different servers isn't the best idea nor making game too grindy with only 1 dura/ship. Having 5 durabilities makes it possible to have almost nonstop pvp if You like it that way.
I would like to see big linefights with big ships. If You have only one dura on your precious 1st rate, you might not want to use it on pvp.
Community would also split into to different groups which isn't too good for development of the game. Like someone said earlier, it would need balancing stuff for two different servers. Also something what suits for hardcore server, might not suit the other.