I do not know anyone using Hollowfang but on paper it looks good. Which of the both sets has more practical uses, if magic users are present?
On of my setups is bogdan, olorime and worm. Symphony is a slot in if needed.Symphony of Blades, Worm Cult, Hollowfang. Tons of sustain for the Mag users.
TL;DR
Sanctuary would do better in terms of healing (100% buff uptime+wider range) than Hollow Fang
Worm would do better in terms of pure sustain (100% buff uptime+ wider range) than Hollow Fang
Hollow Fang falls in a middle-ground if you ask me and can have some nice uses even tho i would not keep it as "standard" set in any dungeon i'd farm it for some specific content where it can shine.