Hi Daniele,
I don't think there is any contention over the idea that miners that control a larger percentage of the hash rate, h / H, have a profitability advantage if you hold all the other variables of the miner's profit equation constant. I think this is important: it is a centralizing factor similar to other economies of scale.
However, that is outside the scope of the result that an individual miner's profit per block is always maximized at a finite block size Q* if Shannon Entropy about each transaction is communicated during the block solution announcement. This result is important because it explains how a minimum fee density exists and it shows how miners cannot create enormous spam blocks for "no cost," for example.
Best regards,
Peter