Kind of obvious really. A multi-platform engine (2.5 I think not 3) vs a custom engine build specifically for the platform. I'd expect MGS4 to run more smoothly.
I wonder what's next for them to compare? Uncharted 2 vs Gears 2? Both 3rd person, etc.
I think if they're going to do this they should at least align it to something more specific - such as comparing pros/cons of custom engines vs off the shelf or something like that.
Otherwise they seem like oddities really.
Try to be reasonable... its easier than you think...







