The original issue (crank flex / bottom end wear) will only present itself on engines with more than four cylinders IMHO as there is only ever one power stroke at one time in a four pot four stroke.
However, with more than this, surely the pistons will be in different positions on the power strokes at any one time, and thus making different power each at any instant anyway - so the problem in effect happens whether you get it perfect or not and is just another thing that the crank has to deal with regardless - or have I got the wrong end of the stick?