Just read your post - very detailed and informative, thanks so much for sharing.

I highly recommend "Moonwalking With Einstein" by Joshua Foer about his experiences training alongside memory championship competitors. Also, working memory tends to be domain-specific and there's little transfer as you mention, see K. Anders Ericsson: http://www.psy.fsu.edu/faculty/ericsson/ericsson.exp.perf.ht...

Really enjoyed your post though, shooting you an email now...