If you are going to wait for a higher z68 board release all you can do for guesswork now is compare the p67 exteme4 and z68 extreme 4.
The p67 extreme 6 has a few more features/vrm etc than the extreme 4 ,I personally am just glad I didnt spend the extra cash on the mr fatality face in the bios p67.
you know the extra features with z68,I think something is dropped compared to p67 ,dual lan? not sure im too lazy to go checking articles,maybe its the fdd connector .
Lets just say If I had been offered a free upgrade to a z68 extreme 4 when I was exchanging my b2 p67 extreme 6 for a b3 I wouldnt have taken it.
If there had been a z68 extreme 6 upgrade for free ,I probably would have tried it.
One other consideration is with a brand new board type there will probably be lots of bios revisions and perhaps a few bugs,even tho z68 is p67 with a couple of bells n whistles or maybe like h67 and p67 combined.
ssd seems to be where its going,as the cost comes down.Hybrid drives are dying out.My 60g sata 2 one has been v reliable since I put it in 6 months ago and no more defrags is good.