Say you hit someone for a 4k Swallow Soul.
4000 * .27 = 1080. IIRC the heal is then increased by 8%, giving you a 1080 * 1.08 = 1166 heal tick.
Whereas on PTS, it's 4000 * .35, resulting in 1400 ticks.
The heal itself is stronger, but you've lost a bit of healing inc from other sources if you have them.
Increase is from 27% of damage done to 35% of damage done.