Sadly, I think the main reason that most of those rehearsal things were never real songs is because you never really know whether you want to release the song or not until you atleast make a pre-production version of it. I dont know if this was the case with songs such as these, but Ill be playing songs with my drummer and bassist, and I'll think it sounds meh, maybe good enough to be released, but then I get to pre-producing it, or recording it on my computer with programmed drums etc, I always rea;oze some things that we were playing sound like shit, and things need to seriously change, and that's where the truly good riffs stick around and I reform the song "in the studio", a lot like what Opeth end up doing on most of the albums after Morningrise. It's kind of sad, because I think the essence of a band's music should be created live, and then re-created onto a record, but with lots of complex music like metal it's the other way around, you produce it, dub guitar over guitar over guitar to get the sound you want, and then simply do your best to reproduce the songs live with however many members you really have. That's one of the main things that makes me drag my ass to concerts, not only for the energy of hearing my favorite songs live, but also to see how well the band can pull off the songs that I know are not %100 suitable to be reproduced live.
But I would also like to hear some of these older tracks, because after all these great albums, you start to wonder if Mikael and Peter ever came up with shitty music hehe...