I rarely use dark heal on my sorc as heals.
I'd say like 80% of my single target heals is innervate with the odd dark infusion when someone drops rly low. In emergencys i like to use recklessness and polarity shift then dark infusion into innervate. so op.
Dark Heal is in an odd place now that they've buffed it's heal by a significant amount. It all boils down to how you're chaining your abilities and your personal style (as well as the other healer in your group and their particular strengths.)
For emergencies, Polarity Shift -> Triage Adrenal -> Resurgence -> Dark Heal -> Recklessness -> Innervate -> Static Barrier.
If the target is good at this point then, self Static Barrier, consume as many times as necessary to top off, then either self Resurgence or Unnatural Preservation or talented Overload depending on my health (as well as others around me). Otherwise Resurgence on target to eat the remaining Recklessness charge. This should all fit inside the Adrenal's benefit period and Polarity Shift should drop off around the last tick of Innervate.
The Resurgence -> Dark Heal is quite compelling as with a decent surge rating/bonus heal, a crit DH will hit for around 5.5 - 6k whereas a normal DI will be around 5.8 with the same stats. Granted a crit DI will be close to 10k... but it's an emergency situation and the extra second to gain 4k more heal could mean wipe or success.
Not saying this is the best, just something I'm testing out as I'm trying to wean myself off of Dark Infusion as the goto heal. I know DH is less force efficient, but really force shouldn't be an issue if you can keep people topped off. I find force is more an issue when I'm trying to catch up due to the long cast time of DI.
Please feel free to comment on my newbness.