I'm kind of on the fence with this one. If I was a builder and I took months, years, if not decades to create a new design that set a new precedent or at least a new tone, I wouldn't want my designs to be copied by tons of other builders. On the flip side, I think if a consumer purchases my product, at that point it's their to do as they please. It's kinda like buying a parcel of land, and then not having the mineral rights.
Now, on the other hand, if I created my own circuit/design/ect., I would apply for a patent so that my design would be protected. I know that in my brand of choice (Mesa/Boogie), they patent their inventions like simulclass, and no other builder could produce an amp that had that feature (Bugera might have, but I don't remember). If a builder wanted to keep their design to themselves, couldn't they patent their design to protect it or retain it exclusively?
To contrast the point above, I'll stick to Mesa/Boogie as an example. Mesa got their start modifying Fender Princetons, and even now in the Mark series, it can draw it's roots to Fender designs. Just like many amp builders around these days, from Bogner to Freidman to the nearly endless list of amp builders, their flagships were based of Marshall JCM/JMP designs. So, from my point of view, they copied another builder's designs and added more features or altered certain designs to create their own product. Should they really be able to say not to make their designs known when they heavily borrowed from someone else?
I don't think it's right to restrict a consumer from posting pics of their amps. If a builder wanted to protect their design, patent it. I've posted gut shots of some of my amps to show the differences in the circuit between a Mark III and a Coliseum Mark III, and to show differences in certain revisions and to show certain mods (like the Mark III+). It was more for educational purposes than to copy a whole amp design. I think I'd be much better for all of us to be able to use things like gut shots to help educate each other and further amp designs in the future.
I don't know of many direct copies of existing amps other than Ceriatone or Bugera that have sold in big numbers, so I don't think that it would steal business away from any decent amp builder. Most of the time, either the model of the amp isn't made anymore (2203, 2204), or the copy (Bugera) is viewed as a lesser quality product. But, then there's the Soldano SLO. Many amp builders tried to copy the SLO, but they added additional features to it that made it their own. From Mesa/Boogie Dual/Triple Rectifiers, Peavey 5150/6505s, Bogner Ubershalls, they were all projects started to copy the SLO, and added Rectification or different parameters to alter the tone further. They all sold HUGE numbers, but they were never seen as a direct replacement for an SLO. In other words, the SLO is just as desirable, if not more desirable because the SLO started them all.
On a side note, getting back to the gooped-up Dumble amps, I remember a while back , the goop was removed from one of Dumble's amps (I can't remember which one specifically), but Dumble's circuit design matches Mesa/Boogie's Mark II boards almost identically. I'll see if I can find the thread, but it was pages and pages long, and I think it was on a different forum...