I own the 5 string Terra Firma... It's my main gigging bass. I like the look, cause it's quite unique being a single cut bass. The string spacing is 19 m so it's preferable cause our song list often covers slap songs. The Bartolini BH1 pickups are kinda deep voicing, so I prefer to pair them with bright strings (I also have another bass with BH1 pickups).
My comment about the 6 string Terra Firma is that for sure it's not gonna be light weight. Mine is 4.4 Kg, so I'm guessing the 6 string would be something in the 5 Kg area. Just for the sake of comparison, I own several 6 string basses and the lightest is SRFF806 which weigh only 3.8 Kg.