MacBook Pro 15" 2.5 GHz Vs 2.8 GH

IF this is the only point of comparison (2.5GHz vs 2.8GHz on the current 15" MBP) you will probably never notice a difference between the two ... unless you are into hardcore video editing, Photoshop or gaming. Even then, a) you will be hard pressed to notice a difference without instruments to measure it and b) there are many other factors that can affect system performance way more than this trivial difference in CPU speed on a top-of-the-line Mac laptop.

If you have the $200 it would take to upgrade to the 2.8GHz CPU, I suggest a better investment would be to apply the money to upgrading to the 1TB Flash Storage or use it to get a good external hard drive to use for backup.

The difference is trivial. I think there are better things to spend an additional $200 on than a +0.3GHz faster cpu. (Like the larger Flash Storage or an external hard drive.)