Updating from 2.3 to 2.3.3 should not be an isstue at all and even less on a uncustomized install w/o plugins and quite new like youir's. No need to worry.
Just upgraded from 2.3.2 from 2.3, the upgrade was smooth and easy. I thought I would have to download and FTP the files to upgrade.
But wouldn't it be nice to have a built-in backup with it!!
I think I will buy that plugin as its the only one. I have a few questions for the developer. If those are answered, I am pulling the trigger.