My 2 cents:
+1 to what Robert said - with one addition - 'Git' the 1.9.2 upgraded to 1.9.19. About 1.9.6 Moodle introduced salted passwords. Best to work that out in 1.9.x before going to 2.
Any add-ons to 1.9.2 Moodle? That shouldn't affect the upgrade to 1.9.19, but if those add-ons do, best to get that worked out before attempting the move to 2. That will come into play with the move to 2. Also, 1.9.x themes are NOT compatible with 2.x - don't even try! ;)
Explaining the 'Git' above ... would seriously consider using git when upgrading the 1.9.2 to 1.9.19. Learning 'git' now will be beneficial not only moving to 2.x but will sort of 'future proof' ones ability to quickly and efficiently update whatever version for whatever reason ... bug fix or version release. Version 2 is a 'work in progress'.
http://docs.moodle.org/24/en/Git_for_Administrators
while the above URL does say 24 the git process works on all versions of Moodle - including your 1.9.x.
The other item ... while 2.2 is required to get to 2.3, would think the eventual goal would be to get to 2.4 (2.4 much improved performance). Be sure to check requirements for not only PHP but MySQL as well before marching upwards.
One 'catch 22' with RHEL (assuming 6.3) ... the mysql server version. RH has always been 'conservative' when it comes to 'latest and greatest' of anything. 2.3 and 2.4 of Moodle will require MySQL 5.1.33. Think, currently, RHEL does have 5.1.66 - but one should do a yum -y update on any new install of OS anyway. There are ways to get the higher versions installed but one might have to use other repos http://bit.ly/Vj6pST. That version of MySQL is compat with 1.9.x. And, like I said, eventually, you'll need the ability to upgrade MySQL when marching onwards and upwards with Moodle.
The other thing I personally find kinda annoying but such is the way with commercial versions ... RHEL entitlements. Make sure you keep that up-2-date (ie, pay the fee) to assure server isn't vulnerable and so one can get updates to PHP and MySQL.
'spirit of sharing', Ken