I thought this might be of use to anyone looking to try out V4 on their existing forum without any risk and on your server - so here's how I did it. As always, make a backup of everything before you start. With this method you do not actually need to back anything up as your original files remain safe, but because I don't want anyone hunting me down because they made a mistake following this guide, BACKUP FIRST. Once I typed this up it looked like a lot, but actually it is straight forward and very safe. First of all make a working mirror of your existing forums In MyPhpAdmin make a copy of your forum dbase, I called mine forums-v4In your Cpanel filemanager, make a copy of your entire forums folder, I called my copy /forums-v4Now edit the config for the new location In your new mirrored location (ie /forums-v4) , edit conf_global in the root and change each mention of the old location to the new location (so in my example, anything that said /forum was changed to /forum-v4It is ESSENTIAL you also change the dbase, to use the new copy you made, not your working version. The field for this is shown below.'sql_database' => 'dbase_forums-v4',Okay so now if you browse to your new mirrored forums at /forums-v4 it should all load up and run fine, a working mirror of your own forums, with new files and a new database. So now to see if the upgrade will work. Upgrade the files Upload the new v4 community suite to your mirrored location /forums-v4 overwriting your new test installRun the upgrader at admin/upgradeTest the new community! Once the upgrade has completed, you should find your new community up and running, with all your existing members and posts at your test url /forums-v4 Play around with it, get some staff to use it for a few days and get to know it. Go V4 Live without compromising your existing forums. Here's the good bit, go live with your new forums while keeping you old ones say, so you can switch back in an instant if required, at anytime. So now we have V4 running, but it is at the wrong URL, we need it running at the original URL. First of all make your existing forums safe, change the remote folder to something else, so I change /forums to /forums-old. Now they are safe, and the dbase is untouched.Now we need to move the new community suite to that location, so change that folder name in my case, I change /forums-v4 to /forumsNow we have a couple of config changes to take account of the location change.open the new conf_global and change all the temp locations to the default location, (so in my example, change every URL pointing to forums-v4, to just /forums. DO NOT change the sql_database field though, as it is already pointing to your new V4 database. V4 has a nasty twist in that board configs are also stored in a separate file called settings.0c6c00beec.ipsstore in a new folder called datastore, so we need to update those locations too. Open this file in a text editor, and change every reference to the temp mirror location (ie -v4) to point to the live location (ie /forums). I think there were 8, use find and replace to catch them all. Save this file and upload it, make sure the extension is correct (.ipsstore).That should be it, browse to your usual forums URL and V4 community should be online. If there are any issues, check all the URLs configs were updated properly, you may have missed one. If it is seriously FUBAR, simply log into your server and change the "forums" folder "forums-v4", then put your original forums back online by simply renaming the folder "forums-old", to "forums" again - bringing it back online because you have not messed with any of its configuration, only renamed its location temporarily. For me this was the best way to try an live upgrade, while keeping my original forums very safe. Hope this helps anyone with the same concerns.