I'm messing with these micros and using the same code on all of the below described cases.
I'm experiencing a power consumption of about 60uA in sleep mode with an xmega 256 A3U QPFN mounted on an STK600 board.When I send the micro to sleep I can observe a power reduction from 20mA (@32MHz-IRC) to 60uA, so I assume that the power state transition does occur.
On a custom board with the same uC model, but in the surface mount flavor, with all the other components unsoldered I experience 149uA in sleep.
Finally, the same code, on another custom board with a xmega 256A3 model (without USB), goes down to 4 or 5 uA [which is reasonable as I also have a linear stepdown)...
Can you provide your experience on these micro's consumption?