When I post on here I try and post from experience rather than hearsay.
We have been installing micro-inverters for three years and have never had a single call back. If we were getting call backs to fail units we would stop installing them.
Can’t say that for string inverters. We have had four call backs to a Power One inverter in the last two years. One of the reasons we switched over to Samill.
If an ENPHASE micro inverter fails in the first five years ENPHASE themselves will undertake and cover all costs of replacing.