I use an MBP to code in both Visual Studio and XCode. My 17" recently died, and I've been using a new 15" for about a week now. I set the screen resolution to 1920 x 1200, same as the old 17", and barely notice the difference.
What I do notice is how sleek and light and _fast_ the new one is, compared to the old one.
I had the same concern you do, but it turned out to be completely unfounded.