I do not have a file for the MX450. Is it possible to use any of the files for the other remotes? If not you should be able to use the pronto hex codes in this thread to set up the remote yourself.http://ps3ir.com/simplemachinesforum/index.php?topic=42.0
If you are able to set it up I would really appreciate it if you would send me your file so I can post it here for others to use.
As far as the PS3IRX1 vs the Pro there are a few advantages to the Pro:
Power On ability.
Single PowerOff command (with the PS3IRX1 you have to keep the remote pointed at the PS3 for about 30 seconds in order for it to properly shut down the PS3).
Direct control of commands like Subtitle, Audio, Angle, Eject, and the color buttons (with the PS3IRX1 you have to bring up the menu using the triangle command and navigate around it and select what you are trying to do).
You could hide the PS3 in another room or inside a cabinet and just have the Pro unit out in the open to receive IR commands (probably not a big deal to you since you have and RF remote setup).