I think really that most Solaris users (and BSD, and OSX), wich actually uses like i Rosegarden on any Linux partition, could be happy to use it on  their preferred and first OS.

Yes, if not the requirement for ALSA I would be using FreeBSD myself (arts and even jackd is supported there now but I doubt that ALSA will ever be seen in any *BSD soon because it very much appears to be an unnecesary "Not Invented Here" API regardless its stated advantages, those can and are being achieved in OSS API).

So right now I run Gentoo Linux... with reluctance and because Linux is essentially the only platform supported by Rosegarden for that sole reason. And I would certainly use Rosegarden more if I could build and run it on my primary OS.