I have never tried with this particular printer model so I cannot garuntee anything. You are welcome to try if you have access to the old version. Afterall, you can't hurt anything if its not allowed.
However, it is very common for HP laserjet products to be backwards restricted when it comes to firmware updates. Very rarely if ever is there a model that allows a rollback on firmware. Usually when there is some kind of a major flaw that warrants a firmware to be rolled back then HP will relase a new firmware version with the previous changes included instead of publishing an older firmware version.
