The instructor course is about teaching the photoreading classes so that they are consistent in covering all the material you need to use photoreading. Since you need to have done the home study course or taken a live seminar to benefit from attending the retreat, so no, it's not like the instructors course it seems to be taking a different direction.
Everything you need to get photoreading working for you really is already in the course. If I read Pete's messages correctly and given that we all already 'know' how to photoread, this retreat is about discovering the deepeer benefits of this skill in our daily lives as well as transferring some of the photoreading skills into other area... Like the accelerative learning state the other areas in our lives we can use that. It seems to me of it will be to help us polish our techniques, explore further uses of the various steps of the system and discover benefits that are usually accidental but can probably be triggered with some deliberate techniques. One of the main benefits will be being amongst like minded people which can propel use to explore how we use photoreading more. On the whole the retreat appears to be 'photoreading taking it further than impressing the boss with your knowledge.' 
Alex
