I believe there are several things going on here. The Reynolds Number effects start to get to the smaller airplanes I think.

Bill, I think I can assume that you are fairly competent in your ability to fly, observe and correct the flight of your airplanes, knowing when a stall is about to occur, knowing just how to nuge the up elevator on landing, etc., so that when you did something to increase the CL of the airfoil you knew how to take advantage of it. It is a carefully considered refined change combined with lots of experience and you end up with a successful change.

Now transfer to a 30inch span model. The little monsters hardly know when you are trying to finesse them much less do anything right. I have a lot of them in the garage of that size and find that the effects of washout is readily noticable, aileron droop - more difficult to determine if you have done anything other than make the change from flying to stall a little more abrubt. Most of my experience along this line has been with a GWS Zero.

A big difference from your monsters.