So that would be an increase in your healing done by 5-6%. I wouldn't say factoring in High Tide efficiency is worth mentioning, as it should already be 99% just with the 4 set. And your talking about 1 of the most optimal bosses for the class trinket.
Mind if I ask you some more in depth details about the logs (don't know how many pulls you did with and without the trinket)
1. Your riptide went up with 25% but how much did the actual HPS you did change? (cause you loose valuable stats for the other spells)
2. The average amount of chain heal hits per cast (does it actually has any notable impact for high tide)
3. overhealing on riptide with and without the trinket