I used to trust Apple updates without question, but after the past few years, no more. I wait until I NEED the update to have my computer function with some new program or equipment. And even then I wait a few weeks to read about the problems. They still have not fixed the issue with Citrix and the new update to the Safari browser.
Good old Windows has all sorts of issues with 'updates', some new Dynamic Link Library that comes with a new program takes out all your other programs. Thus I don't use Windows much. I have a fine tuned version of 7 running with Parallels on my Macs and the updates for that are turned off. I don't surf from that environment, just run two programs...quicken and Handibase. I have not converted to the Mac version of quicken yet, and Handibase stopped developing their mac version.
I have been burned by Epson on updates for my newer (****TY epson printers, that I threw out, had three of the same model) and that update nuked the function of my trusty Epson 2200 Photo printer. (I had backup of the needed files and fixed that). That was back when Epson made good stuff. Ya, perhaps its just the price point for the XP-830 line, but my $79 Brother's laser printer works just fine. And updates for those are turned off. The Epson printer Firmware updates that I was actually allowing messed up my network settings etc. so that was off. LOL.
Yes, if it's not broken, don't fix it!!