You should absolutely get @stephenkendal and co. to speak at your event. Steem is a very different cryptocurrency that's growing and developing and I'm sure this can be one of the popular talks that would provide a fresh perspective on the opportunities that that blockchain and crytocurrency technologies can provide. It's really an interesting example and a case study that is quite different.
Additionally, the graphene technology that Steem is based on has some interesting advantages over many coins like almost instant transactions and no fees.