Well, atleast add some checkpoints. I wont bother playing a track that's so big if I have to go through every laggy part everytime I die. I think I finished the whole SM v1 once, but it was annoying.
I have a question: Since you're adding on v.1, do we have to ride through the previous parts to get to the new parts? It might sound obvious, but I wondered if you had just made some way of going around or upwards to the new parts.