Should I add gps ?

[seaswirl54]

I have an Apelco Loran/gps 6400 and a Apelco 530 fishfinder/plotter. I was wondering if I should add a raystar 120 gps receiver antenna which I could run gps on both units? The raystar 120 cost almost $300, but I would like to get a color fishfinder in the future. Does anyone have these units and how do you like them? I just bough the boat and have never ran these units at all. Thanks in advance.