It gets kinda lame listening to the same boss song.I like the song alot...it just kinda loses its edge,ya know?I think the normal boss music fits Snarby so use it for him.For JK I was thinking maybe a remix of the Jelly levels,into a battle theme.Roarmulus Twins should have some sort of Techno battle music.Since Vanaduke has one of those big beasty natures,and is like the 'Final Boss' of Spiral Knights,I think he should have some sort of Latin lyric song.It might fit him well.
Leave comments,complaints,etc. and Constructive Critisism
I think you're trying to turn this game into your own with all these suggestions. Don't get me wrong, you're free to post suggestions all you like, it's just I see you making suggestions that would require time and energy that would derail the developers' focus on what the game really is.
Anyways, you yourself can change the music to however you want it to be by using your own soundtrack and turning the in-game music off. I don't mean to shoot you down on your suggestion, but really I enjoy the soundtrack already; they don't need to give every boss their own flavor.