[tsubaki]

Having played with the external antenna on mine, the aggrivated loss of signal should be only if covered by a bimini top or foreign stuff.
There is no reason the internal antenna should be an issue other than expected complications.
A T top with the antenna mounted on it would solve the problems (so would hitting the lottery).
Personally, I like the internal antenna's. Less crap to deal with.
BTW mine is the old Humminbird Matrix style.