We consider them to be essentially solid body instruments, because while they are hollow-core construction, the top and back are quite thick and do not resonate like they would on a hollowbody or acoustic. There is no soundboard. Currently Stanley Clarke models including the Brown Bass and all Signature Deluxe models are hollow core as well. The Further guitar is another example of a hollow core guitar.
In my experience, about 75% of the tone comes from the neck with our instruments. I have not been able to hear the difference between solid core and hollow core construction, but it's rare to have 2 instruments side by side that only have that one variable different.