Both the RS1i and the RS2e headphones are fabulous.
Before there was an RS2e, I compared its predecessor, the RS2i, to the RS1i and ended up preferring the RS2i. I compared using 10 acoustic features, also including the original RS1 with buttons as a third headphone in the mix. For each of the 10 rows, the headphone I heard as performing that feature the best is given 3 points (or first place - blue ribbon), second best 2 points (red), and third place yellow (1). I then add total scores.
RS2i excels over RS1 and RS1i at transparency, treble detail (as measured by attack of finger plucking bass string), and powerful organ/brass tones.
I later obtained the RS2e and found it to be even better than the RS2i, which was first place winner above. Here I compare the RS2i, RS2e, and the original buttoned RS2.
RS2e bests the RS2i with even better transparency, visceral subbass, and nearly everything else except soundstage.
Hope this helps! (I
love answering questions like this!)