Some guilds rotate raid starting hours (2-3 different times of day) to accomodate members in different timezones. It works fine in some guilds.
A guild of 40 members or more producing only 16-18k raid tickets? Activity could be better. More raid tickets => more raids => more rewards => more everything.
In the end it's a matter of what you prefer. What would be more fun for you - to stay in your current guild, or to find a more active guild which performs better and has better prospects for the future?