AST, SCH, and 3.4: What stance do I use now?

[ZAZX]

Ever since 3.4 dropped I've noticed a large drop in the amount of WHMs in DF and usually get paired with a SCH on my AST main.

I used to run Diurnal almost constantly, but with Nocturnal actually being fantastic now and giving better shields than SCH (Critlo withstanding), what stance should I be in?

I usually ask the SCH if they want to be Main or Off Healer, and if they say OH I will stay in Noct Stance for the 10% Healing potency and stronger shields, giving the SCH more time to DPS, provide non-shield support, and spend the MP they save on any raising that is required.

Except a lot of the time when I do that, SCHs continue to shield, overwriting my shields with (usually) weaker ones while they're up or just wasting mana on it when I planned to shield.

The 10% Potency boost is incredibly nice when I'm covering the bulk of the healing and its equally as infuriating when I go to Diurnal and the SCH is in Cleric 90% of the time anyway.

Am I making a poor decision here or have people just not become used to there being a Non-Regen Main Healer now?