To me fretless in Death Metal seems to be a good choice from a frequency perspective. For the most part the guitars use a scooped EQ, the vocals try for a low growl, the kick drums are trying for a meaty sound with lots of attack plus 90% of human hearing is midrange so you have 3/4s of the band fighting for 10% of the overall spectrum. Just about every fretless I've ever played/heard has been midrange heavy. To me that's the perfect way to be heard in that genre.
C/S,
Rev J
C/S,
Rev J