1820m here, win 8 64. using all inputs/outputs, with ADAT I/O connected to mixer, and both MIDI ports. Currently at 44.1/24, X2, 8.5.3. Works fine. Using the last drivers published.
I also tested the 0404 usb, with this computer, trying to get the fader port to work. Interface works. Not Faderport.
X2a cured the computer freezing when exiting Sonar.
The main problem I have had with the 1820, win 7 32/64, and win 8 64, is the drivers do not play well with the Faderport. Hence not using the Faderport.