The manufacturers already have forums accessible only to their users. Frankly, I don't think there's much chance of a generic "secrets" forum being very fruitful. Those keen for one are probably those most in need of the "secrets" and those with the secrets have no incentive to share with such people -- even if those people own a/the qualifying product. Sharing among "equals" probably would work but I bet that's a small, very select club. For novices, it's a tough club to get into.
What might work, is a tutorials section where training is offered, for a fee, and registrants'/participants' questions would be entertained any time after attending/purchasing the tutorial. Lecturers could offer whatever courses/tutorials they feel would be popular and these could be provided as videos rather than require a class quorum. Administrative nightmare and the videos would soon be appearing on YouTube or be re-sold, no doubt. Plus, the experts would be more interested in, and make more money at, running a DR business than playing trainer. Another thought, is offering case studies by and based on the experiences of those with more experience. I've found Jared's case studies of great interest. With more details and possibly augmented with video clips/screen grabs, they might be a viable training option for which a subscription could be charged/membership paid.
I'm not sure any of that would work or it would already be available. I suspect that sharing is done as an act of kindness and goodwill, or in return for a favour, not for monitary reasons.
I'll stop blathering now.