25123 vs. 17400 ms if you compare the naval guns of similar size.ROF isn't simply a function of the autoloader, but also the heating of the barrel, which is a serious problem for high velocity guns that also impacted the 75mm L70 tank gun. If you'll note the modern 128mm gun I linked to has a water cooled barrel as did the Green Mace gun of the 1950s (the last and fullest developed AA cannon by any nation).
ROF will of course also be enhanced with an auto loader like the Green Mace had, but that came at the cost of a limited magazine that took 10-15 minutes to reload before it could be used again.
https://en.wikipedia.org/wiki/Green_Mace
In fact it might have been a DP weapon for the British navy's destroyers before cancellation.
That said having even 22mm wider caliber increased the weight of ammo by nearly double, same with the weight of the weapon system; range didn't increase appreciably, especially in the horizontal realm if you're using the same muzzle velocity.
http://www.navweaps.com/Weapons/WNGER_59-55_skc28.php
https://en.m.wikipedia.org/wiki/12.7_cm_SK_C/34_naval_gun
Not a small difference at all, and it makes sense as wind resistance matters more horizontally