I'm not aware if all "differences between SMP and SSP" have been fixed yet as requested on reddit, but one of the bugs which I posted (which was indeed noted) has not yet been fixed. During the loading screen to the Nether, portal sound "travel.ogg" is not played when in Adventure or Survival mode while playing multiplayer, unlike singleplayer.
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My pardons; I did not check and I rushed this ticket.

Related/Duplicate MC-233
I would suggest changing the title of this issue to "Nether Portal sound not playing in Adventure or Survival modes on multiplayer."
The title [MSP/MSP only] is well...