Bigges con? Not really, they're just a new Revision which allows the core to be pushed further in FSB speed.
Just like the Q6600 that are coming out with a GO revision. This was also done with the 5xx series transition to the 6xx series and then the 6x5 series.
So, it's all a processor update which allows a few tricks.
New Revision? New power management and this time a new FSB speed, not bad but I'd rather a Q6600 for $270 myself, except I ain't buying till 2010.