If you upgrade to High Sierra, you will get Safari 13, which is the newest version of Safari. I am using High Sierra and I haven't had any problem with the OS.
If you do upgrade to High Sierra, you need to download the certificate in the discussion below to access some Apple web sites, such as the Support community.
How I solved the Safari 13 and High Sierra problem with idmsa.apple.com unsecure connection (all Apple logins)
https://discussions.apple.com/thread/251211674
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.