2.3 is plenty fast. 2.6 is a minor spec upgrade
The .3 GHz is not worth the extra $200 IMO. It's maybe a 8% performance difference and a potential battery drain and potential increase in heat generation. In my mental gymnastics of justifying the price of the Macbook Pro, I consider that I "invested" the $200 I saved in the overall spec upgrade to 512/16GB instead of an inconsequential spec upgrade of the CPU. I have a PC I built in 2008 with an ancient quad core CPU that is perfectly responsive and useful. Be happy with your 2.3 and consider it a "discount".