I haven't seen much of any reviews of any pico style PSUs, but the G-Unique one that's coming out seems to be the only one that's advertising anything over 200W, and it only does that because it only accepts 12VDC (and thus bypasses having to convert that voltage and, thus have equipment and heat dissipation for it).
If you can do without the PSU on the power socket, HDPlex offerings are solid.