I didn't want to say that it's unballanced, this is how mu is, it's unballanced in some aspects, most games are. (that's what i was trying to say about vrf/bk)
The point i want to make is that it's not 100% percent related to the server that people chose to leave, some did, but not all, and definetely not most did because of the server, it's because of 3rd party related things, like work, lack of time, simple too worked up (because some people really played 10 hours a day for 3 months and that's hard)
Though looking through archives, on the forum, i've seen some really entertaining events for example:
-Pvp arena tournament
-There was a boss, that spawn and people could use a command to instant become lv 400 when they reseted, and everyone could participate in that boss fight, and after it ended everything came to normal.
Those are 2 interesting things, that i wish i see here, but dunno.
They said they'll bring pvp arena and it's been 90 days and i haven't seen it yet xD
So, in my opinion, it s 50/50 why people leave.
P.S. PVP ballancing in mu will never exist to 100% extent, it s how the game it's designed.
Out of all the private servers i think this is one of the most ballanced in terms in pvp/pve (look at Webzen, they have utterly unbalanced pvp)