I'm with Centaurus and john_t.
They are one black snake. Terrain or no.
In the serious corporate world, they are just not on. No precision approach no go, at least in IMC or at night.
So what if they are approved, unless you are seriously current, up to speed and regularly shoot the particular approach, it IMHO, for all intents and purposes does not exist. Especially single pilot ops.
Airline ops with currency and disciplined SOPS are another thing, but still require a very high level of awareness.
They are no mere intelectual exercise in execution.
Pucker factor 10.