Theres a lot of considerations to put into this...it kind of goes down to the fundamentals of Mir as opposed to this specific server.
The most important thing about Euro Mir was that for years there was stability and the certainty that your efforts would remain. I could take a 6 month break and return to my lvl 35 warrior without wondering whether I had wasted my time. So far ACEM2 has been extremely reliable and from what I've seen the team are the most professional (as professional as you can get for Mir) and responsive to date.
The fact that you knew your char was going to be there for ages, plus the high user count, meant 1x exp and rares being rare was feasible. It was completely balanced. This gave longevity. Private servers traditionally have been a shortcut to becoming a powerful high level character on Mir...easy levelling, high stats etc, but players were easily bored upon reaching a peak. Some private servers (like my own) chose to have easy levelling and a whole bunch of new items I created using the old DB Commander, making new maps, new bosses. It was a new experience - people were discovering new items, new stats, new combinations. I made these new items too easy to get as well though, so people got bored, which what is happening now.
Wiping the server and making current rares harder to find probably wouldn't solve anything if I'm honest - you'd have the die hard people who would go out and find them, and then the lazy people, n00bs, or people like me who dont have the time to invest in an online game like I did when I was 15, who just can't be arsed. For me a wipe personally wouldnt change anything - I've only had time to get to lvl 27 in 2 weeks whereas before I would be 40+ in a few days.
I think the answer comes in being innovative and thinking of new ways to keep higher levels interested, while giving the lower levels something to work towards. Think of new items, new names, new stats, new provinces, new temples, and base the fundamentals of each on what we know already works. Make these new items a lot harder to find, and you could be onto something.
We have tons of maps, tons of mob skins, tons of armour and weapon skins. Create an Ancient Woomataurus that drops a super rare Ancient Wooma blade which is dc 18-50. Use the existing themes - Wooma, Zuma, Boars, Bugs, Serpents - add a whole bunch of items for all levels and classes that aren't like "PoWeR SuPeR SwOrD dc 0-100 sc0-100". Everything is there apart from the innovation. White Boar Mace, Red Boar Staff, Black Boar Wand - Zuma Ring, Ronin Blade, Prajna Necklace, dammit create a flipping Koomataurus that can only be killed by 10 people + because its that strong - my point is think outside the box without deviating too far from what already exists in mir. The names are already there. There are things noone uses anymore - SSW, Fate Sword, RedBloodSword, Spirit Blade, Great Axe to an extent, - all redundant. Euro Mir did it themselves with the shitty Mace and BlkDragon Slayer. Why not
I don't think its difficult to add these things, however I only have experience in 1.4 files so I'm a ****ing dinosaur. But I do remember people enjoying my server that I created hundreds of items for, that weren't ridiculously stated. I just didn't do it right because I wasn't as dedicated as this team.
Keep the existing server, the existing mir - just use some imagination and let people discover new stuff again. But it needs work, for sure. In summary:
1. Capable team - check
2. Stable server hosting - check
3. Player numbers - check
4. Leveling time - everyones happy with this
5. Drop rates - high - everyones happy with it but worried about longevity.
6. Items - same items we are used to.
7. Monsters - same we are used to.
Makes sense to develop 6+ 7 rather than tamper with 1-5.
Just my 2 cents. But who gives a **** what I think lool