should I upgrade to high sierra

Since Mojave will be released this fall, you may want to wait for that one - just an idea. On the other hand, I would suggest that you at least download the High Sierra installer and park it somewhere safe just in case you want it at some point since Apple withdraws any older OS as soon as a new one is released.

You should, since High Sierra brings the important APFS update. APFS is much faster and safer than the original Apple HPS Version.

Edit: Also Consider @babowa's statement

"Since Mojave will be released this fall, you may want to wait for that one - just an idea. On the other hand, I would suggest that you at least download the High Sierra installer and park it somewhere safe just in case you want it at some point since Apple withdraws any older OS as soon as a new one is released."

But i'm pretty sure Apple won't withdraw support for older OSX

There is a difference between support and available downloads.

I didn't say they will withdraw support, I did say that HS will no longer be available for download. Apple has withdrawn every OS from the app store once a new OS was introduced and they've done that since Lion was replaced years ago.

So, unless you've downloaded an OS version previously so it will always show in your Purchases section, you will no longer be able to download HS after Mojave is introduced.

Check to make sure your applications are compatible.

Application Compatibility

Also check to make sure there is a compatible driver for your printer.

Do a backup before installing, preferable 2 backups on 2 different drives.

Yes, as far as I know, that was done to accommodate users with older machines (mostly with Snow Leopard) whose devices cannot handle the latest OS. The OP has a 2017. And, unless you have never downloaded either EC or Sierra, there is no way to test it because they will show for you when you sign into the app store - I can't test it.

Yes

I would.

El Capitan and Sierra are still available for download. but there is no guarantee this will be the same for High Sierra.

You are welcome.