I believe I'd agree with Cugel.
To add a couple of points, consider a cleric for a second?
A cleric 'prepares' spells per day, including one spell from his domain.
A cleric can spontaneously convert any prepared spell into a 'cure' or 'inflict' spell ... including his domain spell, if necessary.
Consider the cleric of boccob with the magic domain - he can actually convert an invisibility spell to a cure/inflict...
Now, looking at the feats in question, consider:
A wizard takes SH - but has no 'cure' spells on his list, yet
A bard takes SH - and does, and thus converts any empty spell slot to 'cure'
A wizard takes AD - adding a domain (heal) to his spell repetoire. He can now prepare a 'cure' spell as his 1 domain spell per day... just like the cleric with the domain (heal) could.
The feat AD also adds those spells to the wizard/sorceror/bard class spell list (says so, right there in the feat).
That's more than the Cleric got from the domain - but the cleric got it as a class ability, the wizard is getting it as a feat. The magic domain spells are not 'added' to the class spell list for a cleric taking it... they are only domain spells.
In the case of the arcane caster taking AD - those spells ARE added to the class spell list. So a wizard could choose to prepare them (albeit only if his WIS is high enough) in place of normal aracane spells as well as memorizing the extra domain spell (another cure)- right? I think we all agree on this effect of AD, given the quote ""Each day you prepare (or cast, if you cast spells without preparation) a maximum of one of these domain spells of each level."
Here I'm wishing we had the full quote (tried to find it in thread, but it's not posted - wise of y'all), because that still has some interpretation behind it. However, it specifically states 'these domain spells'... however, AD also add those domain spells to the class list... No different than a cleric taking the heal domain - the cleric can only prepare a maximum of one domain spell per level... but can prepare the same spell from his class spell list...
If you were to take the intrepretation that that the addition of the spells to the spell list doesn't allow that effect... then I'd have to ask...
As a Bard, if I were to take AD (healing) and gain 'CLW' as a Domain spell... Since AD says I can only cast ONE of these domain spells per day, does that mean I can't cast the CLW I already knew after casting it as a domain spell?
If you don't take that debatable intrepretation - if you accept that adding the spells to the spell list means you can prepare them as normal spells as well as a domain spell, then a wizard with SH/AD becomes nearly as good a healer as the cleric - with a completely different spell selection - so long as you are only looking at the 'Cure' Spells... an inefficient methodology, in my opinion. Consider the clerics access to the vigor variants, amongst others, and you should see why it's inefficient to me - Cures are for emergencies - life/death situations that demand healing immediately.
As for the MT vs W w/ AD and SH - what's the goal of the character? If you want to become the most efficient healer possible, then I'd think that a MT with Divine Vigor, Arcane Disciple (Heal), Spontaneous Healer, and Practiced Spellcaster x2 would be the true healing tank - regardless of the interpretation used above...
Just my two cents

I'll leave now and apply some balm to the singed areas the flames hit
