I certainly think A1S2 does not change the feel and only expands the world we get to play in while maintaining the same core mechanics and approach to the game.
The main thing is that it isn't making anything obsolete and it is not by any means exclusive. The cave raid and the spiral hill boss both strictly encourage community involvement with the way the reward distribution works. In our cave runs we have pulled in so many members from the community because it can only help, and why wouldn't we involve other people when we can.
Well, most new content has made old content obsolete or changed core aspects of the original mabi. Few examples are how rafting/exploring around cor for explo xp is basically dead due to the new explo level locations, certain items/enchants introduced has made old locations where they come from/inferior versions come from obsolete. Cypress from the swamps is a good example although there are many more, used to be 1m, almost pretty much auction only as metus was hard as balls (even though I got one cypress from there), now its worth like 200-300k and NO1 buys from auction anymore.
I'm not saying these changes are bad per se, but it is very subjective whether they are:
1. good
2. should happen on a g13 server that's supposed to be ''old school''
And my personal opinion is that most changes have been good and should have happened (albeit some are questionable like how easy the dungeon is where cypress comes from and how often it drops). Although this opinion can differ for others, since I personally do not care for the ''old school'' besides retaining the old combat system perhaps. All I care about is a balanced mabi that's fun to play, and that doesn't involve P2W reforges/buying tons of OP sleep/heal/stun pets etc. (and a mabi where I have decentish ping), which is why live sucks and why I prefer this server much more. I personally welcome most additions live had, as long as they are balanced. If the GMs could magically take some of the skills from live and tune their power to be in line with what we have right now I'd be down for it for example.