Salesforce has 90,000 or so customers. They get a 50% attendance rate.
Here's one reason why: They are selling to the sexy folks with the travel budget - sales, marketing and executives. The CPAs and accounting staff can't afford to go on trips!
Here's another reason why: They are focused on one thing and one thing only so all their content is relevant to all the attendees (mostly anyway). Sage has to split their messages and stuff to cater to many divergent needs.
Here's one more reason: The world of sales is built on a culture of sharpening the saw. Books, audio books, sales seminars, sales workshops, etc. Accounting staff are trained to shut their mouths and do their work.
That's my take. Maybe I should blog about it...