Last week, I installed several instances of Linux Splunk 6.1 from tars an initial install, I was advised by support late in the week that the release had some serious issues at the UI level, maybe others.
Am I better of upgrading my new instances to 6.1.1, or ripping out 6.1 and doing a new install of 6.1.1? I had to put in a significant number of modifications.
If I do the upgrade, how do I proceed and is there documentation. I am having trouble finding it.
You should be fine with the upgrade, see the upgrade topics in the Installation Manual.