You keep your config.. You just want to make sure you have a backup in case the worse case scenario happens and you have to clean install.
99 out 100 you will be fine with just clicking go... But if its really production you have to make sure if the worst happens the down time is minimal.. Or you get yelled at, worse case could be a PSGE (pink slip generating event)..
Any typical enterprise change control process would include backout plan, and recovery.
I have had to fly out to locations for "risky" upgrades of hardware.. And then doing the work at after hours so that you have enough time to even get new hardware onside in the 4 hour support window and back up before production starts again, etc.
The level of precautions needed to be taken depend on the level of production your talking about taking a risk with.. I click update on stuff all the time when there is no SLA for the service ;)
I would say 999 out 1000 just hitting clickity clickity on the update will be fine.. But always plan for the worse ;) Let us know how it goes..