OK, I actually played the levels in the most recent release. I removed Adventure Mode from my copy since Adventure Mode is amazingly awkward with mouselook. Something's wrong if I have to hold the mouse sideways to play (so I don't start moving left/right for no reason).
Wave Ocean Act 1 has seemingly plummeted in framerate. I do not remember the lag in the first beta being that bad. Anyway, on to the rest. The framerate for each stage is still amazingly annoying. The level design for each level makes me just wonder what the heck Sega was thinking when they made these levels. Mach Speed is a terrible concept of theirs, and ironically, W/O Mach Speed was the best in the pack. That says very little. This mod really has no hope, no future, no real redeeming value. Porting stages, especially bad stages, just doesn't work. After playing Dusty Desert, I actually feel that my Red Desert Zone may actually have some sort of chance in the OLDC. It felt like every regular stage consisted of no gameplay except for springs. Without lag, the stages were worthy of 2/10 on average.
So let's look at a better alternative: making your own stages. You want to design a great stage? Look at the greats. I specifically recommend studying Blue Heaven as well as Arid Ruins Zone Acts 1-2 (which was supposed to be in Blue Heaven). Tets can push out good layout after good layout. If you can start making layouts like Tets, then you will succeed in level design. And then for the gimmicks. If you can push out frequent conceptual win like Sonict, that's also going to help a lot.