I don't know if it's only my way of view it but concentrate fire order/dial seems a little underwelming for big ships.
Small ships get often an increase of 50-100% of it's firepower but ships with 4 dice plus get only 25%.
As some have said it's an underused order with some ships.
What about get an extra of 25-50% of the armament rounded down dice with the order. Looking on the % to not make it overpowered but also not let a ship with a blue-red or 3 red get the same benefit from an order than a ship that costs 3 or 4 times the cost.
The actual problems with 50% will be isd and mc 80 than will get between 3-4 extra dice.
It's only toughts about improving an underused order with the ships that by nature will desire to use them more.