If the 606 has enough power for you, then I would give it the nod.
There was a batch of 805/875s that shipped with below spec capacitors which failed when they hit the top of their operating range temprature. It effected both models from all three plants. All are being fixed under warranty, but that doesn't entierly make up for the trauma of seeing the caps self destruct.
If you go 805, this is one of the few times I'd actually suggest a refurb over new.
Of course you can't go wrong by waiting for all of the x06's to be released.