This appears to be a little out of the ordinary and rates quite high as far as workability goes...
Some thoughts:
1. You won't likely be missing out on any "must-have" features if you don't upgrade your OS for one, two, or even three major versions of the Mac OS. I used to recommend that nearly everyone upgrade to the latest OS once it got to the point-two version and all the bugs were worked out. Both to have the latest security features and to be able to run all the latest technology and applications. But now I realize that many folks are too scared/paranoid about endeavoring upon such a task. It is extremely rare that you will miss out on anything critical by not upgrading. Upgrading is nice, but you usually don't HAVE to do it. And I can't remember a time when a previous OS version was one that folks wanted to badly leave behind.
2. If you are going to upgrade, you really should have a complete backup of all of your data FIRST. It's rare, but it's not unheard of that something can go sideways during a major OS upgrade. An upgrade can stress your old hard drive enough to make it decide that it's reached the end of its life. Software incompatibilities can bring your computer to its knees. Once again, it's rare, but it happens. Besides, you should have a complete backup that you maintain anyways, if you like your data. A complete up-to-date backup, especially a clone backup, will allow you to quickly get right back to where you started if things go sideways during an upgrade. Heck, even if your Mac just ups and dies, having a backup allows you to continue like nothing happened with a different Mac.
3. There is no question in my mind that doing a clean install of a major new version of the OS is a much better idea than doing the easier install-in-place upgrade. A clean install usually results in a Mac that's noticeably faster, and it precludes the possibility of there being stay-resident software left behind from the old OS version that will cause a software conflict with a resulting stability or performance hit. A clean install is a much more involved process that takes longer, but it doesn't have to be onerous. I believe that I've posted instructions to Mac-Forums previously on how to do a clean install the easy way, but if there is a demand I'd be happy to post such instructions again. If you are going to spend half an hour to 45 minutes upgrading your OS, why not spend a little extra time to ensure a much more satisfactory result?
4. Keep in mind that the first few days after doing a major OS upgrade that your Mac will be running unusually slowly. This is not because the new OS is slow. It's because the new installation of the Mac OS is doing things in the background like indexing the hard drive and caching things. What you should do is set your Mac not to go to sleep, and allow it to run for two or three days 24/7. Once all the background chores are complete, your Mac should fly.
5. BEFORE you upgrade to a major new version of the Mac OS, you should check to see if any of your mission critical applications will need to either be updated or replaced to run with the new OS. If they aren't compatible, and there is no update yet, or no satisfactory replacement, you should wait to upgrade. There is a nice, free, publicly sourced compatibility database your can check with here:
https://roaringapps.com/apps?platform=osx
6. Likewise, if you have important peripherals that require Macintosh drivers, such as printers and scanners, you should check the manufacturer Web site to see if your model of peripheral needs an updated driver for the new OS, and if so, if the updated drivers are available for download yet. If they aren't...you should wait to upgrade until they are.