I was listening to Tyger today and really enjoying it, singing and all. I also remember listening to the version of Tyger on Rockface and actually really missing the lyrics. It forced me to have a go myself, which wasn't pleasant.
You hit the nail on the head BM. Tangram IS open to interpretation. The others are best left as originals. I'm still struggling with Hyperborea 2008. Again, maybe the original is the best.IMHO