If I recall, Medal of Honor was basically Battlefield with CoD sized maps, and it felt just so wrong. Basically limiting what makes Battlefield good. I remember renting it, and it was so...just lacking.
I think CoD can thrive with bigger maps, but it needs more changes than just big maps. That and the fact all 3 studios are making 'near future to future' setting CoDs is just stupid. They shouldve had one company doing past era CoDs, one doing present, and one doing future. Pretty soon, they will saturate the market with the same Crysis, Killzone type settings.