Hi Guys,
I think that everybody got a part of the answer, due to the field and the plane you are flying.
Physical rules are the reality. You can not compare the residual idle trust from a 2stroke .60 on a relatively high wingloaded plane with a 11/8 prop and a 1.40 with a 15/12 or even 16/14. The theoretical braking speed of a 12 pitch prop at 2200rpm (whitch give around 2000 at zero airspeed) is around 25mph (40km/h) what is just above the stalling speed of a modern 10lbs F3A plane ( plane with a thrust to weight ratio well above one and a wing loading lower that the curare one!) It means that above that speed, the prop brakes, and below that 25mph, the prop pulls. At a relative slow approach speed, the stopped prop brakes around or more that at idle. (At higher speed, it's the opposite due to induced turbulences). About the roll out, when you land on a concrete runway, the stopped engine give you the shorter one, definitely. Just assist to a f3A competition, sometimes, you can see that even good pilotes got problems to stop the plane on 100m runway! The 1.4 is still pulling the ligh airframe! (Some people put foam against the wheels to brakes them) The grass field case is different, his braking action is good but mine is in so bad shape that I prefer to stopped the engine as I will not be able to taxi anyway with the small 2inch wheels and the prop clearance is too limited. About the big 4stroke on a soft engine mount, I don't like to hear those rough really low idlespeed vibrations, I can't imagine the useless stress that it puts on that so light structure, it hurts!
Just my 2 eurocents!
Sorry for the approximate english!
Have fun,
Ben