Yes, the only thing really of concern would maybe be bus powered drives, some consume to much current for some BDP's to drive.
Just to confirm the limit is 500 mA right? There is a typo in the BDP-2 user manual.
On p.4 it states
When connecting port powered USB hard disc drivesnote that each USB port is limited to 50mA.
(50 mA is way too low to be useful)
More likely correctly stated on p.5
Each USB port is limited to 500mA (½ amp) of current on the BDP-2 so we do not recommend USB drives requiring more current than 500ma’s be used if they are going to be powered by the internal USB ports in the BDP-2.
edit: Ripping a CD now on the Dell drive pictured above! I am a little worried that it's overloading the USB port and could damage something on the BDP motherboard, but it's a good proof of concept. After seeing how easy the process is, I can shop for a cheap wall-wart powered drive.