IMHO, big or small improvement has to do with everything you got. If your system is not as refined down to microscopic level then you probably can't tell much difference. Think of it as taking picture with a cheap vs good lens. At 2X3 size, you probably can't tell much difference. At 8X10 size, you might seen some difference with focus and color satuation. At 20X24 blow up print, the difference might be so great that cheap lens image quality is blur, grainy, lots of lens barrel distortion, color mismatched.... At that level, you probably couldn't go back to the cheap lens any more. You just need to figure out where you stand as of now.
