Hello,
Just wanted to add my two cents. Starting version 6.10.8.0 we improved the installation process for the Host (you may have noticed that - there's now .exe Host available and also the installation window changed a bit). The purpose of this improvement was to make sure that the Host service restarts guaranteed after the simple update instead of delegating this task to Windows msi which wasn't always reliable in this respect. So if you are updating from 6.10.8.0 to 6.10.9.0 you are already using the new process (unfortunately, it doesn't work retrospectively, i.e. updating from 6.10.5.0 and earlier to 6.10.9.0 won't trigger this mechanism).
Yet, even with that precaution made there may be situations when Host service may not start due to some reasons, such as a/v software activity or security policy (this is true about Windows Server especially). We cannot control these factors though, unfortunately, and it is up to the user/customer to take them into account.
Thanks.