You're kinda letting it rot and die anyway currently, giving MM8BDM all the attention, and just forgetting about the balance issues this one has.
Why its still being played is because it is fun. And alot of that fun just kept getting better and got more people because it improved (and, well, yeah, the more content to mess around with), but in the long run, if the flaws get too bad, people might just stop playing it.
And i'm quite personally getting sick of the constant marine spam you see daily, and either do nothing about, just watch your teammates kill themselves merely looking at an marine. Or join the marine's team. Hell, might as well call it Marine vs Ghouls! Of course the humans often complain about the Sjas that constantly seem overpowered to them, well i guess he is quite powerfull and difficult to deal with.
Even if its the last update you'll ever do, atleast PLEASE balance the damn thing before you leave it to rot. It seems quite unlikely it will need much more stuff if you're putting all your effort into MM8BDM, so atleast give the people who like it and some of the people who care for its balance an update! It'll just make it more amusing to play when we want to play it for whatever reason.
Its closed to being decently balanced anyway... Ah, the memories of instakill lightning arrows, 3 super powerfull ice arrows, the machinegun ripping through ghouls even better then the hunter's arrows at some point...
If all those balance issues are behind us atleast we can then just play it if there's an active game going on anyway, without being mauled by riotguns or sjas only. Assuming no new issues pop up. :P
Oh, and considering MM8BDM is your current popular project anyway, it doesnt need much new stuff to regain popularity, for all i care its an silent update! What would possibily stop you from updating it? I'm sure many people would love an balance update anyway, plenty of people getting tired of the usual flaws. Personally, i'll be quite happy when its all fixed, hosted on the official, non-laggy servers, and i can just enter it one day and just ENJOY a good ol game of GVH. Maybe just for purely the sake of nostalgia.