One problem with the current state of affairs is that all mirrors of linuxsampler are violating the license. If true, that's a pretty big problem. Here is why I am concerned:
The authors of linuxsampler and libgig have the right to link their own works without regard to GPL. Having done so, they have the right to distribute the work to each of us in any form that they choose. But we do not have the right to redistribute the binary work in turn, because the combined work does not comply with GPL. The source package for linuxsampler can be redistributed, but it appears to me that redistribution of the binary package is prohibited because of the GPL violation.
A quick google search reveals more than 400 matches for "linuxsampler_1.0.0". Four or five of these are linuxsampler.org, but every other case appears to be violating GPL. Current violators include opensuse.org, which seems like a bad thing. I'm actually very concerned about this, and I'm considering whether I should advise them of the problem.
In my opinion, the current "non-commercial use" restriction reflects a confusion of objectives. If a commercial entity embodies linuxsampler in (say) a keyboard, that would take a lot of work, and they would be obligated to release the source code for that work. That is a valid form of contribution to the community, even if it doesn't get the authors paid. If the goal is to move linuxsamplers forward and build a group of funded contributors, the current restriction is counterproductive. If the goal is to get the authors paid, then I have to say (with respect) that GPL wasn't and isn't an appropriate license for the author's goals. Linuxsampler looks like good work. Sometimes cooperation is necessary to gain from this type of good work. It certainly worked very well for my last company.
Speaking as a potential commercial user who would be willing - indeed eager - to pay to move linuxsampler forward if we decide to use it, the current license strikes me as a reason to be cautious. It suggests that the authors are confused about how to properly achieve their goals. This tends to make successful discussions about how to proceed more difficult. In my opinion, the authors should be free to use whatever licensing terms they wish. What I am suggesting is that confused motivation doesn't help, and the license should be consistent with the goals.
If we choose to put funding into the linuxsampler project, that funding would be substantial (hundreds of thousands of dollars) and we would require that the (useful) results be distributed under GPL. Donations are definitely not the right path for us. We will have specific technical requirements that we need to meet, and we will be looking to fund work directed at those objectives. Which means a contract, not just a donation.
If there is one thing that I have learned in 25 years of startup companies it is that issues of ownership and compensation are very personal, and that they "blow up" very easily. Perhaps that would not be true here; the problem from our perspective is that we don't know, and that represents a risk. One way to manage that risk is to simply build our own solution. I would prefer to avoid that, but the issue from a commercial perspective is to manage the balance of risk and cost.
Based on what we can see on the linuxsampler web site, we have questions about the current architecture of linuxsampler. We may be misunderstanding, or we may be wrong about what we think we need. At the moment, the license stops us from looking at the code at all, and without that it is hard to understand (a) where the code is today, and (b) how our picture of sampler architecture actually differs from the linuxsampler picture. There are many aspects of linuxsampler that we think look promising! Problem is: under the current license we can't evaluate. We don't think the authors intended to stop this type of evaluation, but we have to obey what the license says.
So speaking as a potential commercial collaborator, we feel completely stuck. Assuming we get funded, we would like to help this project move forward. But at the moment, we can't do the due diligence that would be necessary to support that decision.
My last company was reasonably successful with a dual-license strategy. If it would be helpful, I would be happy to talk with you about how we made that work. I would also be interested to talk about our questions (in the current company) about linuxsampler and how we might help.