The new pack goes live as soon as we push v0.3 out (fixes an issue with Extra Utilities and updates Thaumcraft). At that time, you will have to use our mod pack (read the sticky post… register if you can’t) and the world will reset. There will be no reimbursements, however, the plus side is because we control world gen/mods this time around we will most likely (see what I did there) not need to reset for 1.6.
Also, unless a major mod update comes out for us (or something is severely broken) we will probably not see another update until the mods are ready for 1.6.
The new world/pack is waiting on two things to go live; Nerdtacular ’13 and version 0.3. After both have happened, we’ll be moving to the new pack.
A preview build of v0.3 is available here (my DropBox). To use it, you have to download MultiMC, create a new 1.5.2 Minecraft instance, then copy the instMods and minecraft folder to the folder MultiMC made. No support will be provided for this method, but its cool if you want to see what we’ve been testing ;).