Hi Pete,
Not sure if you'll be able to get any of the bits at the MMM open day, to my knowledge they only deal in brushed.
Brushless motors are a bit of a new thing to the marine side of RC but have made great inroads in other RC models, as well as most electronically controlled, motorised items available.
It's my firm belief that it will be the future though.
Brushless motors are generally smaller and use less power than their brushed counterparts and, in time, will probably become the norm.
I have found they give excellent torque and much more prolonged runtimes with lower levels of heat buildup. Really the only downside for anyone who wants to become an early adopter now is that supplies are generally limited to online retailers only and sometimes using speed controllers etc that might be more aimed at the RC car market etc.
Alex