wrong transducer

I bought a pontoon with transom mount hummingbird 150 on it , then was given a hummingbird 788 CIhd with no transducer so I just replaced the head unit on the consol and never bought a new transducer for the 788 everything seems to work correctly with the exception of the water temp option which I now see that that is built into the transducer . was wondering if it is worth the time and effort to run a new and correct ducer cable if all I am going to pick up is the temperature option or will new cable have other hidden benefits ?

All you would be getting extra would be the surface water temp. read out like you said the 2D would be the same in both transducers.:twocents