At first I was not paying much attention to thinksound, but I was looking for a balanaced non-fatiguing IEM with good mids and I ended up with Rain over RE0. I was deeply impressed with Rain's beautiful sound signature even out of the box. It's a unique IEM and I listen to a lot of music styles. Rain really worked for everything I played through it. It might become my favorite IEM. The only con was that it is not the most isolating, but I haven't played with tips.
I dont mind it too much though as to hear a little of whats going on outside is not such a bad thing (and certainly safer) and if im going on a plane i'll take my X5s or more RE0s which i find isolate better.
I do agree that in the mids to highs these IEMS are so warm and beautiful.
The sound signature in mids to highs are a little similar to the X5s but the mids on the X5 are a little recessed and the Rains are right there (mmm, beautiful)