Yes, Philips is generally really good about ensuring thier hardware is backwards compatible.  I have tested the Philips 9450 Digital Pocket Memo with the new Philips SpeechExec Pro Dictate software, everything functioned properly.  The software recognized the device and automatically downloaded the files.  Once downloaded, I was able to play the file without issue.

Verification Source: In-house testing 
Testing Date: 9.9.11