I've noticed there are some upcoming training events in March and April for ExtJS 4.0. I don't often go to a product training event, and I want to get the most out of it. There are two that I am interested in, ExtJS 4.0 Update and Mastering ExtJS 4.0. I would consider myself an advanced ExtJS user. I'm comfortable with modifying existing ExtJS applications, as well as creating my own custom components. I also keep up with the Sencha blog, and have watched the videos from the Sencha conference 3 months ago.

My question is, with my experience, is it worth while to go to the ExtJS 4.0 update event or would I feel comfortable with the Mastering ExtJS 4.0 event?