Great question, and one that may be relevant to more people as they start to use SRM.
Mike Laverick who wrote the book on SRM does not cover this, however he is giving it some thought. Not that I speak for the council of the great wise ones.
Moving pages files to a separate disk is not an un-common practice. Windows figures it out if the disk for the page file disappears and recreates it on C. SRM currently has issues with this though, as it wants the datastore replicated (I need to get back into the lab and do some more testing on trying to get this to work).
But this is all digression. To your problem.
Why don'y you just create a new datastore and put the new machines page files onto that one? Sure one is tidy but ... Or create a new large lun and storage vmotion all the disks across with a script. How much bandwidth are you saving? Can you monitor the IO's on that LUN? If you get your memory settings right the machines may not page a lot and it may be okay to not separate the page files, only analysis of your environment will give you the answer.
As to your real question, are people separating page files for mirroring, yes, a quick search on the internet will reveal that traditionally many have been, but its a different question if its right for your environment.
Would be keen to hear what IO rates you are getting on the page datastore.
Considering awarding points if this is of use
Rodos
{size:10px}{color:gray}Consider the use of the helpful or correct buttons to award points.
Blog: http://rodos.haywood.org/{color}{size}
