Allow me to bring this thread back on track

(BTW Jessica Alba is hot

)
I'm not too sure you listened carefully enough if you thought the E4c and E500 sound similar. I urge you to listen again, this time for a longer period of time. The E4c and E500 sound different to me even though they both have the Shure sound signature. I won't tell you what to look out for in case it biases your listening/opinion. It doesn't take golden ears to notice the differences, which aren't that subtle.
Did you not also find the E4c more detailed and refined in general? Coming from Etymotics, I think the best introduction into the Shure line-up is indeed the E4c. The E500 may be too drastic a change.
Of course, YMMV
