The 200x server idea is great. Devs seem like a capable bunch aswell. And thanks to Maxtor you'll get a nice community too.
About S grades, I'd make them with craft. and I'd add a few custom quests for recipes. As far as it goes for mats, I'd totally boost the drop/spoil rate of those in all 65+ zones. Keymats could be dropped by raids. L2 is meant to be a teamplay game, and this would make people cooperate. I'd balance it in a way that'd allow an organised, 10 people clan to make set+weapon+jewels within a week for all members.
I'd make the adena rate insanely low, like 1-5x and the prices for everything adjusted to it. This way adena would always be usefull and you could even get raid jewels for 1-2kkk.
Now for the balance, I'd leave it completely interlude-like, no nerfs to frenzy, ai etc. If it'd be left retail-like, It'd be balanced like it was on retail.
Enchant - well, I'd go for +16 max for weapons, and retail like chances. Also, +12 max for armor. Enchants shouldn't be easy to get, they should require quite a bit of work.
Noblesse & Hero - noblesse should be made by quest only. And the quest should be full. I'd make the reagent pouches drop a lot higher than on retail though. Heroes, should be choosen each month or each 2 weeks. Thats up to the community. Hero skills / weapons should be left retail-like, excluding the hero cancel stick if ALL buffs will be 1h+.
Donations - I'd say +12 weapons and +6 armors [s grade] should be available. Also, donations for noblesse, AIO buffers [if the npc wouldn't have COV etc.], clan levels + clan reputation, what definitely should be EXCLUDED are raid boss jewels. Especially enchanted ones. You could include things like BOGs aswell. It wouldn't be a bad idea to add dynasty armor ingame, with SAME STATS as S grade, obtainable only via donation +major raids like antharas and valakas.
Custom stuff - I'd say adding some kewl custom systems ain't a bad idea. For example, reward system for players. Someting like the pvp reward system on L2Relapse. I disagree with adding any kind of custom item that adds stats though.
PS. the other option is a balanced, Dragon Network-like server with stackable subs. 2 from the same race, though it ain't my style and it requires a lot of work & custom changes to make it balanced.
EDIT:
I forgot about the chronicle, it should be Interlude imo. though a balanced, bugfree, and complete hellbound [or any higher throne, with everything working though] wouldn't be bad either.