Hello, I'm from Brazil and I do not know how to speak English very well so I'll be using google translator, maybe this comment is a little out of coherence.
In my opinion it would be better to launch the 5.1 patch to '' fill '' the server and after a while launch the 6.0 patch that you are working on.
I also believe you would have more time to work on the 6.0 patch because the 5.1 patch is stuffed with new stuff and it would take more time for the players to "get" because they already have all the items in the game / made all runs of the patch.