Just played this and I have to say, this is some outstanding difference from the last version I played. This engine is incredibly accurate, relatively bugless "I didn't find any but 1 by the way" and overall it just generally feels like a proper Genesis Engine. I like all the minor tweaks and fixes that you've done, it does really show. The difference in feel is less than minor.
About that one thing I thought was a bug, I'm saying "thought" because I'm not actually sure if it is or not. When you are about to drown when near a SpecialStageRing, the counter and music still continues. I don't think this will affect the gameplay what so ever if it's fixed or not but above all else a minor nitpic. That's all I could find while playing it twice and I'm usually quite good at finding bugs too. Once again guys, excellent job guys! I'd recommend anyone using any previous version of worlds to port to this one as soon as possible.