Trying to get Malone's bass track on 'In Memory Of' to sound aggressive and heavy was difficult. When Steve DiGiorgio and I were trying to work together, I heard some of his playing with fretted and fretless basses (he does both very well), and would much rather hear his playing with a fretted instrument. Seems like they have too much of a 'jazz' mentality.
Lars is a killer bassist, but after my experience with Sean Malone, I'm a bit hesitant to work with any fretless bassists.