I do not beleive the comparisons between 2 and 4 strokes are made all that easy, to say a .40 2stroke is compared to a whatever 4 stroke would not be all that accurate there are all different types of 2 stroke engines. The .40 fp or the .40 la are probubly the least powerful .40 size engines going, oh i forgot to mention the tower stuff... if you step up to a higher performance 2 stroke engine the same comparison doesnt apply.
I think the comparison should be made between individual engines to be more accurate.
Just a thought .
Most knowledge in R/C is only a matter of oppinion.
But mine is always right he he he