I think I understand where APL 76 is coming from. For years I followed a famous and very proficient sifu who convinced a lot of people that his system of Yip Man Ving Tsun was far more refined and effective than other lineages,
including the branch of YMVT taught by Yip Chun that APL 76 studied. Those of us who did
baisi to this sifu and became his disciples learned the
true version of his system through personal training, not just the publicly taught version, and indeed, just like APL, we could immediately see and feel the difference! Just like what APL 76 says about his Sum Nung lineage training.
...Oh, perhaps a few did not really "get it" and were not able to benefit from this more refined teaching and quit. Perhaps they were better off with the simpler, public version of WC. But those of us who really worked at the finer points reaped the benefit, we got the real secret sauce.
Unfortunately, many if not most of those subtle differences
only work in the kwoon, or playing the
chi sau game as your particular system plays it. At any rate these stylistic "secrets" haven't given any WC/VT/WT branch an objectively quantifiable advantage in any form of open fighting contest that I have seen. Far from it! Yes, a few tough and talented proponents may emerge from each special lineage, but to date there is no objective evidence that these kind of technical "secrets" consistently make any positive difference in real contests.
Is there a difference between close "indoor" training and superficial public instruction.
Absolutely. Of course, great athletes working privately with great coaches will learn much more than what someone going to a weekend seminar or watching video by the same coach will learn. But in the final analysis, this is the result of intensive coaching. There is nothing gained by excessive secrecy. Only by open and transparent comparison and objective testing can WC/VT/WT progress as other fighting arts have. At least that's how I've come to see things.