And since the OP said he'll be using those applications, this is all completely relevant!For the OP's uses, the better graphics card will make no difference. The only place he might make use of it is in Keynote, but $300 to make Keynote animations render a tiny bit quicker seems like poor financial planning to me.
The 9400M is a very capable chip, and more than sufficient for 99% of what most users will be doing. Your money is better spent on RAM and storage upgrades.
Maybe I'm old fashioned, but why purchase a MBP if you're not going for the discrete graphics? If the OP wants to save money and only get the weaker 9400 then he should opt for the 13" variant.