I would be happy to harvest at this stage. THC levels are at their peak purity at this maturity. After this the THC starts to break down into CBD and CBN, amongst other compounds, producing a sleepy and heavy, zombie like stone. I much prefer to get high and up-lifted, not zoned out. Everyone has their own preferences, so it is up to the individual and what sort of stone they prefer.
Look at the pictures that the breeders put on their websites when advertising their products. Nearly all will show flowers with 5% or so, of white pistils still remaining. This is for a reason. Once all the pistils are brown, the plant is basically at deaths' door with degraded THC.
But, each to their own.
Like you said, "all his buds are top shelf". Hope this helps..... Organoman.