Well I purchased my first Grado, a SR-60E that I got for portable though I ended up using it more for my desktop system as they sound better and scale more than I expected. Seems I'm really liking the Grado sound, much more liquid and round than I expected. I'm liking it more than I expected I would, especially considering I'm coming from much more expensive headphones. Some reason I always forgot to get a Grado. The treble while a bit aggressive(especially before the initial burn-in) isn't really fatiguing to me, especially on tubes. Main issue I noticed is a bit of glare but I assume because it's the low-end model and slight confusion with more complicated music. No real issues with comfort even with the stock pads. I am planning on tinkering with mods on this headphone, will start with simple dampening mods. I'm not sure what to expect from higher end Grado, though I would like to get a pair that's a bit darker, has a cleaner sound, and has a bit better transients. I have no clue how the different models of the E-series of Grados are supposed to differ from each other. Would like some suggestions on what direction I should go in the Grado line-up.
while I don't have that many models (SR-60i, SR-80i, SR-225i, SR-225e, RS2e and have heard RS1e, GS-1000i/e, PS-500e), I have found that the SR-225e is the sweet spot in price to performance to me and with some mods can be made to get to the RS2e level in some ways. Biggest change is taking the SR series driver and putting them in wood cups, with some sorbothane on the back of the driver and some dynamat around the cups it helps to clean up the sound and smooth out the over all sound.