Anytime you install a transducer inside-the-hull of a fiberglass boat there will be some level of signal loss. However, if you do a good job of installation this will be negligible and can usually be overcome with an increase in the Sensitivity menu.

I don’t know that I would wait on the inside-the-hull version transducer as it is the same exact transducer except that it comes with an epoxy kit instead of the transom mount hardware.