This is textbook and 100 percent correct.IMO when they turn amber, you are losing potency because things are starting to degrade. The Couchlock effect verus an up, head high is more in the genetics and whether it's sativa or indica. So I agree with Jorge. I wouldn't use trichs as the sole means of determining readiness. The pistils should not only be orange, but they should appear to be receding into the bud, as the bud does its final swell.
So ya gotta have an overall feel for ripeness.