Between September 25-28th there is a new magic convention featuring 3 awesome mentalists: Max Maven, Anthony Darkstone and Menny Lindenfeld( the inventor of Hollo, Chaos and Carpenter's nightmare)as well as non mentalist headliners.
They about to reveal lots of hidden secrets that were never exposed before.....
You'd better check: http://www.mars.org.il

Is this really the best way of learning mentalism, or a shill for a magic convention?

It is the best way to learn from the headliners themselves.
I attended many conventions in Europe, USA and Mexico.
Every time I attended conventions I learned so much and got improved of what I do.
Currently, I perform for all major corporations in Israel as Amdocs, Teva, Intel, Microsoft and more.
Learning from the best got me where I am today, and I am still learning and improving all the time.
How about this as an answer to your question?

Roei,
If you are interested in attending a convention that will add to your knowledge as a mentalist, I recommend you attend the Mindvention in Las Vegas, Nevada USA this November.