I'm definitely on the side of horizontal scaling but I put this out there because I know you guys are also invested and like the game so I'm not gonna make a decision like this myself. Since the start I've always said I'm making this for the majority so if I add a system that only a select few would enjoy then I've lost the mark and you guys wouldn't want to play either.
Tbh we aren't even doing vertical scaling in a sense, the level rate is ridiculous and you can press ez to get to lvl 100 in 3 days, If we took that away would people still want to grind? I mean old GOA style with better Anti-Ez systems in place (I can make one that would stop the majority of ezing.. I used to be an ezer)
There's always people I see come on for 5 minutes and be like "nah I aint grinding again" or something like that before asking for auto 100 then shortly after we don't see them again.
I played the old GOA I remember running A ranks with squads a whole night just to gain one level before going to sleep. These days if I play a game for 30 minutes and don't see any real progression I'm probably putting it off for a while or not coming back, people have less time, well in my case anyway.
I do see where you are coming from with the boring side of it, everyone is already level cap so what's there to do? - Those are the kind of things I was hoping would be discussed, I've always liked the idea of more events.. ranked events, Great Ninja Wars e.t.c
Either way as I said before, this all depends on what everyone else thinks. I will work on whichever system is the winner :p