By moving the limitations from the per-day basis to the per-encounter basis, you essentially remove surges as the primary basis for when players decide to rest.
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But in my experience, players quickly see through the mechanics, resolving to not put themselves into that position in the first place.
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If the number of surges you can use per encounter is limited, we attain this goal.
If the number of surges you can use per day is unlimited, or at least the penalties for running out are mitigated, we solve the other problem, the 15-minute adventuring day too (by making pressing on a real choice, a hard choice).
I would raise a caution with this, especially given that you have players who seek to exploit the healing mechanics. You will need to also redefine what constitutes an encounter, or under what circumstances you can take a short rest.
As it stands, there is nothing mechanical to keep players from resting five minutes to let all the per-encounter stuff to reset, use it, then rest up another five minutes to let it all repeat again; in fact, I've even had it somewhat encouraged RPGA games. If you make the daily surges unlimited, then there really is no continually growing threat, and really no hard choice about pressing on.
Because being down your daily powers, but in all other ways equally viable going into ecounter 6 as you were going into encounter 1? Not really a hard choice at all, if there is even one scrap of plot reason to press on.
So perhaps just introducing per-encounter limits, but maintaining per-day limits, will give you the balance you are seeking.
I'm going to additionally suggest that if you go with encounter limits, you scale them differently for different characters. Two methods come to mind for this:
A) By class role. Make 3 be your median, and adjust up or down from there; 2 for controllers, 3 for leaders and strikers, and 4 for defenders
B) By limiting it to a fraction of the character's total Healing Surge per Day limit, either 1/3 or 1/2.
I would lean towards (B) using 1/3 daily totals, rounding 1/3 HS down and 2/3 HS up (ex. 10 HS/D =3 HS/E, 11=4). This seems to be the best suited to maintain the class-specific needs for more or less healing surges, based on their intrinsic design function. (e.g. Paladins will likely have more capability than Fighters, because they'll be using them for others as well as themselves, and Avengers and Barbarians will have more than other strikers, because they are primarily in the thick of melee and may need a little more.)
-Dan'L