Hi Daren,
In the past we have had some engines on the Prony Brake giving people an opportunity to fire under load. So far, I don't know of anyone that has volunteered their engine. I won't be at Steam School this year, it conflicts with another show every now and again. Dan K and Bob D are planning to be around the Brake. I haven't heard from others. If you ask, they will certainly 'saw logs' with you, 20sec of load and then 20sec of no load or whatever you decide.
Have a good weekend,
Jerry Chistiansen