Tools Upgrade Complexity
Applying FULL PUM upgrade is easy (we've done it). Its all automated and you use your existing environment / setup.
Is it correct to say that a Tools upgrade (even from say 8.58 to 8.60) is a lot more complex? It looks from the documentation that you're essentially rebuilding all of your domains/environment. Any special things you did to setup those environments (installing web server certificates, configuring key stores) would have to be done from scratch. You may also need to install other software (drivers, etc.).