Hi Ismael,
A valid concern, probably, but one anybody developing GPL code could have!
That's true, but in this case the risk is higher than usual. Firstly because music hardware companies have poor awareness of the GPL, compared to say... network hardware companies (and some of them are bad enough). Secondly, because LinuxSampler can run as a headless node, so it would be very easy to hide the code in a 'black box' appliance.
I would see no problem on that. Even although new code was not GPL, existing code would have to continue being GPL. So it would take not much time for a fork to take place.
Rather than fork, I think it would be better to work with the original developers if at all possible. I personally don't have a big problem with the GPL exception, because I think all downstream commercial users should support upstream free software developers - with cold, hard cash if required. I commend the LinuxSampler developers for trying to keep their software close to GPL, without that freedom being abused - it's a hard balance to achieve.
I moderate a spanish forum on Linux audio and people there love 64 Studio, even although there's Musix and their developers talk spanish!
Musix is a good distro, but it's aimed at a different use case. We should have a Spanish language forum on our new website, even though my own Spanish isn't much better than ¡hola, amigo! :-)
Cheers! Daniel