Language Monitors and Bi-directional Printing: What functionality is lost when disabling? What else uses them?

Question

Server OS: Windows 2008 R2 Standard
Function: Primary Domain Controller and Print Server
Clients: All are running Windows 7 Pro 64-Bit SP1
We're considering disabling the HP Universal Print Driver Language Monitor and in-turn Bi-directional Printing due to potential server spooler instabilities, before we do this the IT Manager wants to be sure:
1. What functionality is lost when disabling Language Monitors and Bi-directional Printing?
2. What else uses Language Monitors and Bi-directional Printing them? In other words what may break?
3. What specifically do Language Monitors and Bi-directional Printing provide?
Thanks

Answer 1

Alan (or anyone else):
We're testing disabling the language monitor/bidirectional printing for one particular printer.
Can I confirm this is the procedure for disabling a particular print queue's Language Monitor and Bidirectional Printing? -
1. Locate the relevant Language Monitor registry key in: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Monitors
Either delete or rename the registry key (so it cannot be found), in my case: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Print\Monitors\HPMLM121
I renamed it to have the date at the end (HPMLM121_2015-01-29).
2. Inside the above registry key is a DLL file mentioned under the DRIVER reference. In my case it's called: hpmlm121.dll.
I searched the entire C drive on the server and this was only found in C:\Windows\System32. I moved this elsewhere out of C:\Windows and also renamed the DLL too.
Therefore preventing Windows from being able to find/use it.
3. I then unticked Bidirectional Printing Support in the Printer Properties Ports tab of the printer in question.
4. Lastly either restart the server (or stop/restart the Spooler service).
I've done all this and the HP Print Notifications for Replace Cartridge etc... are still active.
Any idea why this is?
Thanks