Scrap healing power
You don’t have to be level 80. You can head to the Mists, stack it using free PvP gear, then fight one of the duelling bots and see how much it adds to your self heal.
Healing actually scales really well on my necro when stacked enough. Take well of blood for instance (my personal choice of heal fro necro). Without +heal it has about a 6.2k base heal and 200 per tick every second. With the healing factored in, it has a base heal of almost 9k, with every tick healing 700. Math factored in no heal stat = about 8k, with heal stat = about 15k almost double and all from like 1233 to heal stat. Healing has a place, it is just underused because very few classes have multiple skills to utilize it. On my necro it scales with regen from the staff 2, the MH dagger 2 life drain, as well as the regen from 4 on the offhand focus.
Many Wiki entries on skills have data on the healing power coefficient already filled in.
For example, http://wiki.guildwars2.com/wiki/Healing_Signet
“increases by around Healing Power * 0.0325 per second”
That’s 3 HP per tick for every 100 healing power, when level 80 characters have 5 digit hit points, and are hit for 4 digit numbers. Not even an exotic in every slot is going to turn you into Wolverine, it seems.