So, the conceit of the item is that it is balanced with other items and retains something effectively identical to the cleric's magical healing ability.
The problem as I see it is that the conceit just doesn't work out. I hope I can explain how my reasoning goes, even if you may not agree.
Trying to break up a cleric's powers and evaluating them against each other might work out something like this (Using the 3E cleric here as I am more familiar with that one than NEXT).
3 Spells (non-healing)
3 Spells (healing)
1 Fighting ability
1 Channel energy
1 Feats
Spells make up about 2/3 of the cleric's contribution to a party, and half of that is healing. So 1/3 of the cleric's worth is in healing. Conversely, the sum of all feats gained is about 1/9 of the total contribution. Lets assume the same is true for other classes - feats (excluding bonus feats) is about 1/9 of each class' total contribution. If you sacrifice all feats to gain a non-class healing ability, it should be about 1/3 as effective as a cleric at healing. About as good as a bard I guess. Not a team "leader" on only it's healing merit.
These numbers are taken out of thin air. Not all clerics spend half their spells on healing, and you might slightly change the evaluation of the different abilities in other ways. I didn't even touch skills. But the basic premise remains; feats are but a small part of what a character is. Even spending all on them to get a certain ability won't be very impressive. And I doubt this is going to change a lot in Next, even if there has been talk of making feats fewer and more significant.
The same goes for items. An item that mimics the portion of his spellcasting arsenal a cleric puts into healing would cost much more than the expected equipment budget of that cleric. If it didn't, what would be the use of spellcasting classes - you could just get the equivalent "security" item, "fireball" item, and "healing" item and replace both the rogue, cleric, and wizard. Everyone could have the solid base of the fighter with the versatility of a an additional class.
Now, if there was no healing class at all this might work. Let me try to think about this too. If there is no healing cleric to use as a yardstick, if healing is a completely optional element anyone can have, your idea might work. Say it costs 1/4 of your feats to be able to act as the party healer, about as good at this as you'd expect a cleric to be. But then, why don't everyone make that investment... If they do, you suddenly end up with a 4 person party that gets the toolkit of 4 normal characters AND 4 healers*. Choosing this cheap option is just too good, unless there are other options of equal worth to compete with it. And if there is, we get back to my above example where you replace the wizard with the "fireball" kit and so on. Ops, seems this doesn't work either.
Now, I would not mind if this was possible. I have nothing in principle against your idea - I just don't think it is workable. I'd like more customization options, that more of a characters omph was in feats and other customizable elements. But it is not the direction I see Next going - quite the opposite in fact. Next seems to focus more on the core abilities of each class and push the customizables into certain niches (such as skills). And most people seem to like this.
I think this is the point Neonchameleon has been trying to make - that only a class ability can pull the weight he wants the warlord to carry. No optional character option will be enough - except possibly one available to all, like second wind was.
* (note from above) Barring action economy - they don't have the actions of 8 people, they just have the toolkit of 8 people. Or actually, since healing makes up about 1/3 of the toolkit of the cleric, they end up with the toolkit of 5.22 people [they get 1/3 of a class (healing) by spending 1/36 of a class (1/4 of all feats). Net gain 11/36 of a class each or just under 1/3 extra]. Still a very attractive option.