It seems that Peace Walker has quite the development resources behind it.
Source: http://www.examiner.com/examiner/x-...eace-Walkers-development-team-as-big-as-MGS4sExaminer said:Peace Walkers development team as big as MGS4s
Hideo Kojima stated last year that Metal Gear Solid: Peace Walker would have been called Metal Gear Solid 5 if it wasnt coming out on the PSP. He and his colleagues at Kojima Productions seem to be backing up that claim, at least when it comes to the size of the development team.
In the latest Kojima Productions Report podcast, Sean Eyestone stated that the upcoming PSP game has just as many people as MGS4. They have hundreds of people working on the project and staff was added for the game. He later mentioned that, in some ways, its even bigger than Metal Gear Solid 4.
He and the rest of the hosts then went on to discuss how Metal Gear Solid: Peace Walker was misconceived for being a PSP game. They echoed Hideo Kojimas previous statement about the upcoming portable title having the most content in the series (including Metal Gear Solid 4: Guns of the Patriots).