I like this server for Tekkit Survival. I have played tekkit for years and this is one of the most activ and fun servers I have been on. Like all Tekkit servers it does get block lag at time but its bearable and the staff is great and on top of rude/grieffing players.
I am having the same problem...I have tried building 3 different worlds and saving chunks every time the world loads. Using Windows 7 with the latest build.