Brian,
I agree that a scale performance category would be interesting and would certainly make IMAC even more like full scale IAC aerobatics.
My idea in the other thread was a displacement/weight/wingspan restriction to keep power to weight values similar to full scale planes.
@Pistolera commented that the best full scale can do is roughly one to one so that should be an upper limit for IMAC.
FWIW, in full scale if a pilot has an upline with two rolling maneuvers then he/she is anticipating the energy needed to make that upline while he/she is completing the maneuver before. If the sequence is designed properly then there's going to be a downline right before it to build up the speed and the pilot will be full throttle all of the way down the upline to be able to carry the weight of the plane all of the way through the next upline. It isn't just horsepower, it's planning and anticipation of what's next that keeps things going from figure to figure. That's what I think is weird about IMAC, there's no reference to scale performance and, IMHO, it keeps IMAC from being as awesome as it should be.
In the interest of full disclosure, I've never flown in an IMAC contest. I was working on becoming an IAC judge and was building a full scale Pitts S1-SS at one point so I definitely have an interest in precision aerobatics but life presented me with a fork in the road which I had to take and so I haven't been involved full scale or IMAC ever since.
I'd like to try IMAC, maybe later this year if I can get a flying habit going, but the scale performance thing would be a really cool element to add that would challenge even the best pilots to do better.
for example.....
50cc, minimum weight might be 22 or 23 pounds and minimum wingspan might be 90" in order to get good long uplines but not half throttle, unlimited vertical uplines.
so you make a chart with engine displacements, minimum weights and minimum wingspans to get everyone performing similarly like in full scale and watch as guys have to relearn how to time an upline so that they're not falling over on their backs after two rolls in the vertical followed by a hammerhead or humpty.
now you're talking scale!