Don't know for a certainty what the 4mb update does, but when it installed it did NOT restart my passport or give me a prompt to do so on my own. When I restarted manually I noticed two things. Enhanced 4g LTE services are now connected and the wifi calling indicator is on and stays on. Neither of these was true immediately after the large update.
I have two Z30s. So far have only updated one. This is the daily driver one. The other one has a second number and lives in my car for emergencies. I also have a Z10 and a Classic that I will sell because they are decorating my desk drawer LOL.
I am partial to the Z30s.