The more common school of thinking goes DET > SS > Crit for secondary stats.

Personally I see them as about equal.

SS is also good for chain casting, landing important heals faster, and pre-casting/cancelling heals more rapidly.

I think crit gets a bad rap. Crit is better for enhancing our hots, something SS doesn't fare so well at, and are a huge aid in recovering from big attacks. If my tank gets smashed while I'm in the middle of casting Cure I, a crit is helpful. Likewise for Cure 3 recovery from boss nukes.