If i follow the following article and change OA URL name also instead of keeping same, do you see any issue?

http://blogs.technet.com/b/exchange/archive/2013/07/17/357445

Hi SMF,

no, there is no issues expected. The only thing to remember is that you need to adjust your 2013 CAS systems first. Please also keep in mind that, in case you also switch AD sites in case the servers deployed to a new namespace need to match the sites (or scopes) where your mailbox servers live.

Regards,
Martin

"The only thing to remember is that you need to adjust your 2013 CAS systems first.", what about if i do before this? to let 2010 clients where are Outlook 2010 to use OA with new name