First: It's a swordmage power.
Second: Quoting myself, I said "it's not that far away", and proceeded to explain why. Yes, you spend no surge at all on this power, and Healing Word does use a surge. Barring circumstances during which time is of the essence, both can be used to optimize healing. Healing Word does it a lot quicker than Unicorn's Touch, but it uses surges, meaing that the latter might be faster in the long run (never needing to take an extended rest due to running out of surges).
My main point was that this usage of these powers seems more or less to require the same from the story/DM, meaning that you don't have to mind these shenanigans (a lot of DM's I saw post on here already got an apoplexy from repeated uses of Healing Word and short rests... this would be worse in their book), and there can't be any timing in the storyline. IMO, though, if time is of no importance anyway, why do you care if they can heal without using surges all day long? They might just as well use HW, and use extended rests when one of them runs out of surges.
Yeah, there's a modicum of difference, but only in specific storylines and campaigns, in which the DM can call shenanigans on it all.