The answer is never.
If you want what the Axe III offers, including the features and pace of updates, get an Axe III. To use an analogy, the Axe III is like a pool at a resort with a spa, nice landscaping, and frequent upkeep. The FM3 is like an above-ground pool in your back yard. You can swim in both and do some things with the above ground, but it’s never going to be what the former is.
If you want what the Axe III offers, including the features and pace of updates, get an Axe III. To use an analogy, the Axe III is like a pool at a resort with a spa, nice landscaping, and frequent upkeep. The FM3 is like an above-ground pool in your back yard. You can swim in both and do some things with the above ground, but it’s never going to be what the former is.