From what I can tell so far, the primary difference between your scheme and OHANDA seems to be that it is focused on people? In particular, OHANDA approves their trademark for use per-project. And in your Open Hardware Contract scheme, the idea is that members are signed on and are then allowed to apply the trademark to their projects as they wish. When the members assign the trademark improperly or violate the you-may-use-the-trademark license, their membership (and license to use the trademark; or an individual instance of a license to use the trademark for a particular purpose) is revoked. Is that how this goes?
When releasing designs, schematics, source code and other files on the web, how does this handle derivatives? Only distributors/users who wish to keep the trademark would have to meet the trademark licensing requirements. So as a hardware and software developer, would I tack on "All rights reserved" and provide a copyright license (GPL, CC-BY-SA, BSD, MIT, whatever) that ties in with anyone who has a license for the trademark? In this specific question I really only care about people who are following the rules of course. Requiring the developer to be a licensee of the trademark probably violates some part of, say, the GPL about non-discrimination?
Again, I'd really like to make sure derivative reciprocal licensing can work. Right now it seems to be ensuring derivative/reciprocal licensing as long as the derivator wants to keep the trademark (and possibly if he wants to protect himself against patent litigation). But there are many cases where software/hardware should be open source where it's derivative of open source but not making enough money to be be worth the cost of patent litigation. Because of the way the probability distribution works, the majority of derivatives will probably fall in that area (between making $0 to making $200k+ or whatever the minimum is that lawyers are OK with going after).
So the threat of patent litigation wouldn't make developers or legal entities want to join on board the trademark train if they are under that $200k/year zone where patent litigation really starts mattering. I suppose one mitigating factor is that they would want to join in against patent litigation if they are starting a business and want to keep their eggs in order. However, they could also easily not care about that possible threat if the patent pool (from the trademark organization) doesn't have any patents that actually concern the hardware in question, so you're back to square one. Maybe if the pool is aggressively growing (a la the Defensive Patent License and "Fair Troll" growth scenario) it would be enough for these people to jump on board?
Finally, would a co-op make the most sense for a member-owned trademark? IIRC, SPI worked as an LLC then became a 501c3?