Better defense, yup!!! The Japanese would have overrun the Bataan Peninsula many times over, if it wasn't for the umbrella of 14 inch rifles and 12 inch mortars on Corrigidor island and Ft Drum... The Japs bombed and shelled them countless times, but many were still operating when the Americans finally surrendered.. While they were still in American hands, NO Japanese ship went ANYWHERE NEAR Manila Bay...
The whole Japanese Malaya campaign was conducted, because the IJN didn't want ANY PART of those guns on Singapore island.. But in that case, the Brits didn't install them with 360deg traverse.. Bigtime error!!! If they HAD been able to use them in the overland defence, that story would have been COMPLETELY different!!!
Unlike the "Bizarro large" german Gustav type railroad guns, these coastal guns had a good rate of fire... And although they were vulnerable to air attack in open emplacements, they were very simple, robust, and easily repaired.. You could put them out of action for awhile, but it was quite difficult to completely destroy them!!!
RC