VCM has been used by honda since 2003 (first in the JDM Honda Inspire) and has since been used in the Odyssey, Pilot, and Accord Hybrid...all without any mechanical issues that i've heard/read about. granted, the accord V6 VCM is the largest scale implementation of it that honda has ever done thus far, but that just means they are comfortable with the technology enough to use it widely. furthermore, the VCM mechanism is nothing more than a variation of good ol' VTEC which has been used for decades without ANY reliability problems at ALL.
so theres nothing to worry about with the actual VCM mechanism causing any sort of catastrophic mechanical failure. however, the active engine mounts and active noise canceling can cause vibration and 'booming' issues if they are out of tune. but thats more of an inconvenience than a true reliability/mechanical issue (ie: it wont leave you stranded).
