You could replace the GT52 with the GT54 as the Echomap Plus is compatible, but just partially. On the Plus unit, you would have access to 2D, 800khz ClearVu, and and 455kHz SideVu. But, you would not have access to the UHD frequency SideVu (1,200 kHz). The GT54 will share from the Echomap Plus to the Ultra via ethernet. As with all transducers, running multiple transducers at the same frequency will cause crosstalk interference. Running them at different frequencies will minimize interference.