As of right now I don’t feel that a single heal possess enough ‘umpfh’ to justify sitting on Ancestral Swiftness, waiting for an emergency situation to occur. What I do really depends on the fight, sometimes I use UL and then pop AS right before a big hit is inbound on the group leading to a great snipe with Chain Heal (Assuming the group is topped). Other than that it can be used as a utility tool, meaning that you use it to cast Healing Rain or Chain Heal on the move.
The talent is best used when popped frequently otherwise it will lose value, so try and feel an encounter out, see where you can use the additional heal on the move or the additional tool for sniping. 😀