I run a couple of ASUS 270's in CrossFire and they aren't that bad. Sure, the heatsink isn't as huge as 270X's (ASUS or MSI) but it does the job at reasonable temps ( <75c) and doing so, quietly, with only 2 PCI-E cables. It retains the same amount of power phases of its bigger brother (270X) minus one or two phases for memory. It can run at 1100 GPU, 1500 memory on stock voltage, so I am happy.
For once, the Long Idle mode is working as it should. I am impressed and pleasantly shocked (after bad experiences with the 7000 series), they must have finally fixed it. IMO, this is a great bonus for running multiple cards. Saves a ton of power. It's nice to get up in the morning and seeing both fans turned off and the rig consuming only 25W in this mode. Hopefully, Maxwell will come up with something similar, as I am eager to build an nVIDIA SLI system soon.