Elecraft has announced a new SDR based QRP rig covering 80-10m (not 160m and 6m) which is available ready-built only. It is considerably smaller than the KX3. It can house an internal ATU and LiIon battery and can produce up to 10W. I have no idea how good the RX is. It is likely to be considerably less to buy than the KX3.
See www.elecraft.com .