Hey,
All good here.
I too went the E3 to E4 route and then the fragility of the E4's became an issue as I primarily use the Shure at the gym while exercising hard. Lots of chances to pull them out and put them back as people come up to yack. The SE310 have done far better in this regard as they are heartier construction externally. The sound quality is as good as the E4 with maybe the slightest loss of brightness. This is however made up for at the low end and I like the overall switch with my music. If you are not hard on the earphones, the bright vs. bass issue is worth taking some sample music to a store and comparing on. I think a true audiophile may find a preference one way or the other on this point.
All that said, a traveler will certainly prefer the SE310 construction as the noise isolating is far superior on the SE series. I think though that this is primarily due to the black soft conical sleeves. Love them!
If you can swing it the SE series has impressed me mightily, but bear in mind that my own personal filter is largely tied to the construction in combinatioon with the sound. The sound issue alone will require sample music and a bit of time with the product, pre-purchase.
Not much help but the short very value judgement oriented answer to your original question is: "better".
Come by ORD on 9/2 for lunch and I will let you have a listen if you want.
Mike
Thanks for the comments, I will give it a shot then
To think that the E4 is already so quiet.
9/2, possible, I might have to fly to PVG or HKG for 2-3 days but let's see.