Yeah, personally I think so. While Stars Die covers a lot of ground, it does lack a few amazing songs from the earlier albums. I think it covers the debut (On the Sunday of Life) pretty good, Nostalgia Factory, Radioactive Toy, Nine Cats and And the Swallows Dance Above the Sun are probably the best 4 songs on the album.
As for Up the Downstair, Stars Die doesn't have Always Never, Burning Sky or Small Fish (all are really great), and as for The Sky Moves Sideways it doesn't have The Moon Touches Your Shoulder, Dislocated Day or Moonloop.
So you might miss out on stuff, but you could still get it, and if you really like it, you could always pick up the first 3 studio albums later on. I don't know if you have it, but Coma Divine is an amazing live album that features songs from the first four albums. Personally I think it's their best live release.