IMO SS isn't a good choice. Heals per sec is going be slightly worse and so is mp per heal.
The way I see it, you only benefit if very, very specific conditions are met:
* the target would have died in the if the heal was four to five hundredths of a second later
And
* benediction / swiftcast (and pom in some cases) are on cooldown
* weren't able to anticipate and cast early (or stoneskin in some cases)
The only thing you really requirement to benefit from the det:
* you didn't over heal.