The black wind howls... One among you will shortly perish...
I am in a simular position. I can get the Big Box set or wait for the 5th edition. Not sure which is the better choice. The Big Box set has all the expansions I could want, however I heard that there were misprints on the board.
On the other hand I could wait for the 5th edition, the street date varies from Sept 15 to December. The video from GenCon said early in September, but the online store I buy my games have it listed as 4th quarter.
Just take whichever you see in stores. The editions are so frequent and the changes so minor (I'm probably mistaken, but wasn't the big selling point of the 5th a new box cover and no tuck boxes?) it's just ridiculous.