Howdy, I am going to upgrade MuraCMS to MasaCMS for now to deal with the security vulnerabilities. If I could find theme/front end designers for Masa CMS I would be there long term!! Anyway, we are in a load balanced situation with installs on three servers. My question is if I run core update on one server, that will update the DB as well. I would then need to manually add all files to the other instances for this to succeed. Is there a smaller package of changed files to accelerate updating other installs?

Yes, you should keep all your sites on the same level of code. As for it breaking, it depends on how it's all configured, if the site data is live, how long your cache is, and so on and so forth. You are better off setting up SiteX Site Y SiteZ on Shared storage or mirrored storage (if you do not have shared storage) then you just update the code once, and the database once and you're done.