Still, you seem to have a very low rate of attrition. If each character even spent 1 healing surge during each encounter (not out of character for a lower-level encounter), you'd have your sorcerer running out by halfway through the day!
With some quick math, it looks like your 2/encounter/character figure works out to an average of 10 total surges per encounter being depleted from the "average" party. It really doesn't seem like your party is hitting even half that, at least not early in the day! Your "two defenders" party would seem to be quite survivable even at that rate (though it doesn't look like you have a leader?).
The leader is a hybrid archer ranger-cleric. Then there is a paladin (who has 4 LoH per day), a dwarf (minor second wind with Cloak of the Walking Wounded, plus cleric multi-class), a chaos sorcerer and (at the time) a wizard (since reborn as an invoker).
Party-wide healing surges:
*Fighter 14 (17 CON, Dwarven Durability, and also Toughness for more hp and hence higher surge value);
*Paladin 13 (16 CON);
*Ranger-Cleric 8 (15 CON);
*Sorcerer 7 (13 CON);
*Wizard 7 (12 CON).
That's 49 in total. Now, having just recounted my encounter list, I see 9 significant combat encounters (plus a 7th level combat encounter - that was a negotiation with a trapped Yochlol that went badly for the Yochlol - and 3 skill challenges, only 1 of which would have inflicted damage, and that on only one PC, namely, the sorcerer).
Let's treat every PC's actual hit points as being worth another 3 surges (in fact, the ranger went into the final 2 combats at 3 hp, and in the final combat fell unconscious and had to be revived with one of the new-style healing potions that can grant surgeless healing in extremis - that's more than 3 surges, but I can't swear that every other PC was bloodied at the end of it). That's another 15, for 64 in total.
I can't remember all the surgeless healing from the ranger-cleric's power, but there were two surgeless surge-recovery items used: Dwarven Armour, and the Healing Star of Pelor (a home-made item converted from the d20 Eden Odyssey scenario "Wonders out of Time"). That brings it up to 66. Which, divided by 9 encounters, is more than 7 surges lost per encounter. That's close to three quarters of my "10 per encounter" calculation.
It sounds to me like your PC's are finding it significantly easier than any 4e group I've been a part of (and the general reaction of the groups I've been a part of is that the PC's are pretty dang robust -- I've seen exactly one legit character death (from a poorly-balanced minion monster in the DDI), and nothing even close to a TPK).
The wizard died recently (a necessar precondition to rebirth as an invoker) - you can read about it
here.
As to whether my group has it easier or harder - as I said, there seems to be a wide spectrum of experience.
You say this, but then the numbers don't quite add up. Unless your Sorcerer has a Constitution of 26 (which is, I suppose, totally possible!), there's no way that character could be experiencing this pace in each encounter.
On the contrary - the sorcerer feels it more than anyone but the fighter, I think, because he has a lot of close attacks (as a drow, he uses his Cloud of Darkness to make these viable). But he doesn't generally feel the pressure in terms of damage - he uses a range of interrupts and reactions - Dragonflame Mantle, Swift Escape, Narrow Escape and Slaad's Gambit - to mitigate attacks. It's only once these have all been soaked that the damage starts cutting in.
Other forms of damage mitigation - like powers that grant temporary hit points or damage reduction - are also used by the party.
That's one of the things I very much enjoy about 4e - it doesn't play exclusively as an attrition game (at least, not as my group plays it). Hit point and surge attrition is there, but there is a whole other layer of move and counter move which comes into play before damage is even a factor.
And even when it comes to damage mitigation by healing, there is a lot of scope for tactical play. In the fight against either Calastryx or the mooncalves (I can't remember now), the PCs had one daily item use left, two healing words left (fighter and ranger), one surge on the fighter, no surges on the ranger-cleric or sorcerer, and one surge on the wizard. The fighter had two healing daily item powers - dwarven armour, and symbol of shared healing. After quite a bit of deliberation and calculation, the fighter dwarven armoured and then healing worded himself, while the ranger then healing worded the wizard on the ranger's turn. If the symbol of shared healing had been used instead to bring up the wizard, the ranger's healing word could not have been used on the fighter until the ranger's turn, which would have been too late - because Calastryx was doing too much damage.
My group, at least, feels under pressure when survival turns on that degree of tactical accuracy. (It was a somewhat comparable
failure of tactical play a few sessions later that led to the wizard dying.)
But even your experience, anomalous as it seems to me, doesn't escape the reach of that balance math. You might give your spellcasters more spells so they can do useful things more often, but ultimately, the numbers still work.
Which numbers? If I'm trying to balance (say) encounter powers against daily powers, how many encounters should I factor in between rests? The 9 that took place in the episode we're talking about? The 1 that took place in a more recent session (3 PCs vs 2 15th level rock hurler gargoyles, a 14th(?) level dire rat swarm, and a 13th (?) level solo troll - the wererats vacated the PC's new tower in response to a court order, but left behind some lodgers)?
Encounter powers that are balanced against the daily powers for the long day will be somewhat overshadowed by the daily power nova-ing that took place on the short day!
And it's not just a balance of mechanical effectiveness. It's also about a balance of choices and spotlight. Different suites of abilities with different recharge times make it less likely, I think, that every player will have a comparable range of choices in a wide variety of scenarios, and comparably many chances to make his/her PC's distinctive mark on the encounter.
