I would say try jlpt 4 (or maybe 3 if you're comfortable with it) to get a feel of the test at that exact moment, the "atmosphere" there if you have not taken it before. No harm taking it right? Or if you have the hobby of collecting certs.. try all
I once joked with a friend. He mentioned he wanted to take lvl4, but felt that lvl4 is uselss, so i suggest that he take lvl3. but lvl3 compared to lvl2 is nothing. Then go straight to lvl2. And yet again, why take lvl2 when you can have lvl1? In the end, just take lvl1 ba!
btw, yukaguri you were a linguistics major? Coool! I totally can understand on the part about you loving grammar heh. EL? I'm planning to go for a masters program at waseda or TUFS.