I don't believe what he is saying about the rooster vs. production to be true. Like I said before, hens in a healthy setting that are not being overbred or overcrowded or anything like that should not be negatively affected by roosters. A roo shouldn't effect the regular 25ish hours it takes to...
What does your current flock consist of? The only disadvantages of having less roosters is that not all of your hens would be covered by him, (fewer fertile eggs) and your flock might not be quite as well protected if they free range.
If you don't have too many roosters for the amount of hens and space you have, then whether you have a roo or not does not effect egg production. However, if you have too many roos and too little space, or he focuses on one hen and puts stress on her, I would imagine her production may go down.