SubBD lacks the coverage necessary to beat common stuff, Chesnaught has to rely on its 2 move coverage to sweep. Alongside Drain Punch, if Grass is picked, stuff like Dragonite, Venusaur, Heracross, Celebi, Altaria etc. would be able to tank a hit even at +6; if Rock is picked, Slowbro, Gallade, Hippowdon would have no problem taking a hit and KOing in return; Ground obviously gets walled by the Lando, Latias, Gliscor etc. What's more is that many of said mons I listed are pretty common switch ins to Chesnaught in the first place, so it might be challenging to get a sweep going. Sub-Endeavor, however, gives up the ability to sweep unprepared teams to being able to handle prepared teams better, since only priority (which stops SubBD too) and Ghost types can avoid being cut down to 1 HP with Endeavor.If you're going to run Sub-Salac you're probably better off using the Belly Drum set with Overgrow, since it can sweep unprepared teams on its own.
I'm not trying to say which set is better because what 1 set can do, the other set can't do, simply because the comparison goes both ways; 1 set can run through an unprepared team with ease, while another set fares better against teams with natural counters to Chesnaught.
That being said, I'm voting for ZANBAKUresh's Super Fang Chesnaught