Is expanded polystryene foam a bad idea for a basement?

I am going to be using rigid foam to insulate my basement during a new-home construction. From what I have read, extruded polystryene is preferable as it is closed-cell and a vapour barrier is not required. What I have not been able to find out is if there is any problem with using expanded polystryene with a vapour barrier instead? I have read a fair bit that says ONLY use extruded, but I cannot figure out why?

I know that I will get a small R-value benefit with extruded, but extruded will be double the price.

Any particularly good reason not to use expanded foam?