In general, no (not from 2.8.1 to 3.0.2 as I recall.) But I would play it safe by backing up the database, moodledata folder, and even your moodle folder before doing the upgrade.
I also run an experimental moodle. I always update my experimental moodle before updating my production moodle.
Maybe others here on Moodle.org will provide their thoughts about the upgrade from 2.8 to 3.0.
What is stopping you from upgrading to 3.1.1+?
Thanks for your message Rick,
Could you please advise me on how to create a second (experimental) Moodle site?
And yes, there is no reason why I couldn't upgrade to 3.1.1 (I just wasn't aware of it before!).
Leon
Here are the general steps:
1) Create a second database, such as moodleexp.
2) Create a second moodledata folder, such as moodledataexp.
3) Download your desired version of moodle.
4) Unpack it into its own folder, calling it something like moodleexp.
5) Go to it in your browser, such as www.yourdomain.com/moodleexp. Let it install itself.
Eventually, move your production database data into the experimental database, and your production moodledata into your experimental moodledataexp folder.
