Isolation is very good, on par with most BA IEMs and the Atrios. I commute by multiple trains and have no issues.
I cannot see a vent hole.
I can barely remember the XBA-3, so take this with a grain of salt. The XBA-3 was very much "BA" quality bass, better than all single/duals and on par with bass tuned triple driver IEMs. There was no comparison to dynamic driver bass, little rumble, deep but not sub-bass deep, if you know what I mean. The XBA-H1 is very much dynamic driver bass, so is an order of magnitude more bassy than the XBA-3. It depends which type you prefer.
Hope this helps.
Edited by evilking - 10/16/13 at 3:02am