You will see that MHz difference if you are into music/video encoding, no where else.
Other factors that will have a better effect on the speed of your Mac are a faster RPM hard drive (or having an SSD instead of an HDD) and more RAM.
That small MHz difference isn't enough to be noticeable in everyday activities.
Oh, this suggestion is regardless of what happens today or tomorrow (any future MacBook updates). Rule of thumb is, small MHz differences account for nothing; unless you render, encode or decode a lot.