... can only comment on 31.5. It is the best I've tried (vs jadis, denon, krell, marantz). As I understand, .5 upgrade is mechanical upgrade (ie the lid etc). Drawbacks (again for 31.5) - the laser mechanism is in the open. Therefore, if you have kids who play with things, or very dusty / hairy (pets) environment, this might not be a good choice. Sonicly, however, it is unbeatable (16/44.1).