Is 2.16 ghz upgrade worth it?.......It depends
The overall speed bump will be range from 0% to 8% depending upon what application you are using and even what process you are doing within that application. Applications that heavily depend on the HD or the graphics card will see almost no difference in speed. Also, remember that the 2.16 GHz still has the same on CPU cache memory and the computer has the same speed of RAM that the 2.0 GHz has.
The RAM, CPU cache, HD, system bus, and graphics card do not change with this upgrade and most CPU's already max out these bottlenecks. In almost every real world test I have seen you at least cut in half the CPU speed %increase to half. In this case you would actually see about a 4% average increase........you won't even notice it.
However, if you render video for hours every day or apply major Photoshop filters all day long for your living then your % increase may be a bit more over all at around 5% - 6% and may be worth your $300 investment over time. But for 90% of the users out there, the extra .16 GHz is just a feel good purchase.
If you haven't already done so, increase youre RAM first, and your HD second.....investments that will most likely produce a major increase in overall speed for the same or in the case of the 7200 rpm HD, a much smaller investment. I myself am sticking with the 2.0 GHz MacBook Pro with my 2 gb of RAM and a 7200 RPM drive and buying a new iPod Video with my $300 bucks. I guarantee I will get more use and enjoyment out of that $300 investment.