Yea but that blacjack guy has only had his sandbed for 2 years. It will be working awesomely yea, but in another 3-5 years time, he will most likely not have a healthy looking tank anymore if he doesn't do anything with his sand
Some people say they're good, some say bad, some don't care, but the amount of tanks with a DSB that have crashed after 5 years is phenominal.
I am not realy speaking from experience no. I started my old marine tank with a substrate, but it just collected so much crap in it that i took it out, and it was way better.
Its up to you whether you run one, but i'd advise pulling out quarter or half the sand every 6 months or so and giving it a good rinse out in fresh saltwater as this should prevent too much crap building up in it, causing a crash in the future.