Oh, a few more things:
Emerald Coast and XSRB2 do NOT get along, and even after using vanilla SRB2, I notice tons of ceilings are offlevel with varying heights which look ugly (and I don't recall the other versions having that issue). Might wanna fix that, and maybe tone down the water; IIRC, there is water beyond the thok barrier, which may be causing errors not only in XSRB2, but some graphical errors in Vanilla SRB2. Emerald Coast MRX's lighthouse has REDFLR under a part of it, and if you die and respawn in a checkpoint after the music change, the music switches back to the first tune. In Final Boss Zone, in the area with all the Crawlas, there's one Modern Crawla there by accident. Also, why have Remix mode in the unlockables if it's by default? Just a hangover you didn't delete yet? And the Megamix preview is selectable without all the emblems; I just got some emblems (not even enough for mirror) and 7 emeralds. And finally, you may want to discard the level select option and replace it with a room having multiple exits to the levels, so players can't exploit having Pandora's Box open. Oh, and you may want to start using some of the new 2.0 textures in some of the Remix and Megamix levels. You know, to make them look more fresh.
Also, may I use the Silver Ring Monitor and invisible spring SOCs? I would love to use the Silver Ring Monitor in my OLDC level, and the invisible spring may come in handy for a few things.