daylight savings is a pain in the arse to deal with.
Since it depends on where the server is really located and if the host sets it or not. Or in your case you don't use it all and the host might.
The ubb control panel server time just reads the server and the posts will be based on that time setting.
So I would just set the ubb time offset to be what you want it to be.
Then members outside of your time zone will need to adjust the preferences to their time settings.
