True VANOS failures- hard failure of the whole vanos- is rare.
More likely we seen vanos solenoid failures- both solenoid failures and o-ring seal failures. $1000 for a board. and hour to install.
M5 is pretty expensive to keep running perfectly- death by 1000 cuts.... if you cannot DIY it can be very painful. Especially since it is a $73,000 car that people buy for $15k..and zero repair/maintenance history.
Keep it as simple as possible...but no simpler.