I agree sort of, most manaufacturers recomend an engine range and do not qualify it i.e. "recomended engines .10 -.25" now heres what they should add ".10 will NOT ROG and needs JATO, flies real mushy at all times" and for the top end " .25 flies perectly if weight is under 10oz, for all weights above 10oz use a .40 engine"
if they were honest the engine would go UP several sizes and they would scare away the guys on realy limited $$$ this is MOSTLY true for the smaller sized planes.