I don't think it really applies as much with model engines. Usually a short stroke engine has less piston speeds or acceleration inertial stresses than what you would see with a long stroke engine. But model engines being small already don't quite have the stresses one sees in large full size engines.

The vintage engines all tended to be long stroke designs many years ago. Not too many were short stroke engines back then. But as time passed more and more engines came out with shorter strokes to allow for more RPMs. so at the time the accepted practice was to have a long stroke engine and some engine designs had really long strokes too.

Now a long stroke engine can still out perform a short stroke engine. The intake ports, bypass ports, and exhaust ports typically have a longer duration in how long they are open as compared to a short stroke engine. Thus they can breathe a little better and develop more power. You see this with the classic .60 or 10cc pattern plane engines. The pattern plane long stroke engine usually out performed its short stroke bretheren. also a long stroke engine tends to develop more torque than the short stroke engine does.

The short stroke engines of today, tend to be overbored engines trying to max out the displacement in a smaller crankcase. For example taking a .45 engine and boring it out to make it a .55 engine. These overbored engines usually wind up where the cylinder sleeve now impinges and restricts the air/fuel flow through the passages into the combustion chamber, thus becoming flow restricted. But if the engine had a pretty large crankcase and crankshaft design to start with, it is less of a problem, than you see with a engine design where the crankcase is a little smaller.

I would think that it looks like having a stroke being a little larger than the piston bore is probably getting close to optimum. The model diesel engines tend to behave differently and breathe differently than the glow or gasoline engines do. But not by much though. Maybe a 5 to 10 percent difference between them.