I'll chime in, as I attended the same seminar when it was held at the Beale Aero Club at MYV earlier this summer..........
If you need an excuse to fly somewhere (RBL has one of the best airport breakfasts, IMHO) or participate in the Wings program and need some hours, it is probably worthwhile to attend.
If you are going thinking you are gonna learn somethin', and you've been hanging around here a while or have a strong interest in backcountry flying, you'll probably be disappointed.
The two hour session was primarily filled with two partial videos, one from Sparky Imeson and another from the Utah or Idaho BCP, I can't remember which. I hadn't seen either before, but was a little pissed when he decided they had run long enough and just turned the videos off without finishing them.
There was some general discussion of mountain flying issues bookending the videos - density altitude, mountain winds, ridge crossing, et al.
I'd think if you have the patience to read Sparky's book, Potts' book or any other information on the subject, you'd learn considerably more than what is presented in the session. To be fair, Les, the presenter, is an extremely knowledgeable guy regarding many of the issues surrounding mountain flying, but the presentation wasn't exactly compelling.