as for june 08, the FSA and econ has a lot of changes plus u don't have the option to use other source for studying co'z the CFA text (again) are included in the fee. so its up to your personal assesment if there is no much pressure and u can prepare enought for the dec exam then go for it, and if u pass, you really save time and $$$ but in the other hand, if u are not certain then u must consider the 08 june batch.