So I finally got my 4p today and have been playing around with it ... it seems the Riptide procced by the set bonus is Spell ID #185875 ( http://www.wowhead.com/spell=185875/riptide ) and not #61295 ( http://www.wowhead.com/spell=61295/riptide ) which is the standard casted Riptide. What this means is my targets have 2 different riptides on them if it procs onto a target which I had hardcasted on already (i.e - a tank I had Riptide on, then targeted with Chain Heal and the 4pc procced). The procced Riptide does not overrite the original Riptide as they are different spells.
Spell ID #185875 tooltip reads "Heals a friendly target for (138% of Spell power) and an additional (180% of Spell power) over 18 sec. Your Chain Heal spell is 25% more effective when the primary target is affected by your Riptide."
That's effectively the "old" Riptide from last tier. Does this mean that with the T18 4p I should go back to the healing model from the previous tier and prioritizing the targets with Riptide for Chain Heals (obviously only the procced Riptides) or is it a tool tip bug? I will dig into the logs a bit and look, but I figured I'd hit this forum first and ask.