Upgrade or clean install?

I am using owncloud 8.1 stable one a raspberry pi 2 with resbian in my home network with an external HDD with the user folder on it.
For some quite now I have some troubles with my contacts. I cannot create, edit or delete contacts in my owncloud.

I got the recommendation to upgrade my owncloud. But the upgrade path seems ridiculous
8.1.0 -> latest 8.1.x -> latest 8.2.x -> latest 9.0.x -> latest 9.1.x
I would prefer a clean install of the latest version.
What do I need care of before I make a clean install?
I have no shared content. I use my owncloud to sync /backup my few documents and as a Google calender and contacts replacement. So I could export my contacts, calender and todo-list as a file, make a clean install with 9.x and just import my contacts, calender and to do list again. And since my user folder is on the external HDD and don't need to care about this right?

Same scenario here - OC just as local Calendar- and Addressbook Server.
I did - and would do again - a clean install and migrate Addressbook and Calendars via VCF/ICS/CSV files.

I agree, that a fresh install is faster and/or better. In my experience, every step of your upgrade-chain might fail, producing additional work.

… especially upgrading Address Books from 8.2.x to 9.0.x and 9.1 is not the least-problem-area.

So a clean install it is. Thank you!
I hope I don't forget anything.
User folder is on the externa HDD so nothing to back up there.
Calendar and Contacts will be exported
How do I remove my old owncloud the right way?

I did the upgrade chain all the way from 7 -> 8.0 -> 8.1 -> 8.2 -> 9.0 -> 9.1 and while there were some minor annoyances and procedural nuances to be taken into account, it went off without a hitch.

The surprise update to 10.0.0 has been worked through with the final exception being no bookmarks app as of yet. It appears that 10.0.0 is no longer in the stable repo, though, so you shouldn't find yourself ambushed by that.

How long did you need for this upgrade process?