Now that I've spent some time with both, I've noticed that the IE600 has a slightly V-shaped sound compared to the Pilgrim, which leans more towards a U-shaped tuning. The bass on the IE600 is exceptional and I believe many, myself included, will really enjoy this aspect—it's just so satisfying. However, the Pilgrim offers more detail in the bass compared to the IE600, with an excellent textured response. While it may not have the same impact or slam as the IE600, its bass is still quite impressive.
In terms of treble, the IE600 can sometimes be a bit too much for me, especially when listening to rock, metal, and EDM. However, it performs well with orchestral classical music and pop genres. On the other hand, the Pilgrim's treble is much more to my liking, as it is incredibly detailed without ever becoming harsh or sibilant.
When it comes to detail, I find that they are quite similar in the mid-range, with the Pilgrim having a slight edge. The Pilgrim also offers much more detailed bass and higher quality, detailed treble compared to the IE600.