Karyn Romeis, in her comments, offered a great idea for developing a SuperUser community. I am going to add her comment verbatim:
I am particularly familiar with the issue of lack of incentive for superusers. When you are fatuously told that the kudos is enough,you want to strangle somebody. One of the reasons I found for the dropped ball scenario is that the superusers were often drawn from the support staff and junior to many of the people they would be supporting. When the line manager is one of said people and suffers from insecurity issues... well that's not a very promising cocktail!
One measure I have tried in the past was to generate a superuser community. The first port of call for everyone else was the superuser. The superuser's first point of escalation was to the superuser community before going to the IT helpdesk.
One small suggestion (forgive me if I'm stepping out of line, here): when you do the demos in your superusers workshop, how about getting some of the proficient ones to do the demo to small groups within the class? This will help them not to be bored by a process they already know, while generating a nice ratio for each demo group.
Karyn: I hope you don't mind - but I'm going to pass these ideas on to the other trainers. I'll keep you informed of their reaction.
BTW - everyone needs to check out her blogs! Great stuff!
http://karynromeis.blogspot.com and http://karynromeis.edublogs.org