A fresh upgrade is just backup, plain install, restore. It's super reliable but somewhat inconvenient and time consuming.
A package upgrade is easier for friends of the command line but runs the risk of leaving your computer with an inconsistent package selection or configuration. And it's less used so bugs are more likely.
I tried a package upgrade for 14->15, worked great. shrug I did 15->16 a few days ago reinstalling fresh (wanted to disable encrypted home directories, figured this was the easiest way to do it). Worked great too.
A package upgrade is easier for friends of the command line but runs the risk of leaving your computer with an inconsistent package selection or configuration. And it's less used so bugs are more likely.
I tried a package upgrade for 14->15, worked great. shrug I did 15->16 a few days ago reinstalling fresh (wanted to disable encrypted home directories, figured this was the easiest way to do it). Worked great too.