That's actually right, I've heard a lot of people saying the Spectors have very good balance and another whole bunch, myself included, not digging their ergos at all.
I've had plenty of Fender, and some were balanced, some were not and had a tremendous neck dive. Fenders under 4kg usually neck dive, without light tuners.
the worst was an American Vintage '74 Jazz, natural finish, a beauty to see, 3.5kg, so light, but ne headstock went down heavily, and all the weight killed my left shoulder.
the same model, but at 4kg, was extremely balanced, even with a nylon strap.
my Euro4 LX is pretty well balanced, not the best but it stays where I put it.
PS: the Thunderbird is unbalanced only due to the strap-button position behind the neck. in 2012-2014 they moved the pin toward the neck (and body edge) for about 2cm, and it became one of the most balanced bass I've ever owned.
in 2014/2015 they went back to the standard position of the pin...