As chance would have it, we have a -02 380 SX(dad's) and a -02 520 SX(mine) in the carage. I used to ride a -00 YZ250 before the big thumper. I have ridden the 380 extensively, as well as the -01 model.
Both have their advantages. From what I've found, the 520 is actually less tiring when you ride it properly. I just don't get arm pump at all. However, you better ride it correctly, since when you try and throw it around like a two-stroke, it will take its toll very quickly and tire you out completely breathless-like.
The only two-stroke I can see myself going back to is the 380, I just need the power to have fun. For now the advantages of the four-stroke outweigh those of the two-strokes for me.
BTW the -02 suspension is a vast improvement over the -01 (dad had a 380 SX), and I think -00 to -01 was not much of a change. Too bad the EXC only gets 43 mm forks but with revised internals, I think.