DP at 7% is far too strong considering you're not giving up anything close to what other healers give up.
to put it in perspective it takes 18 seconds for a pally to gen 3 HP to use DP (7%) mana, likewise it takes 16 seconds for a MW to get back 8% mana. i would rather sacrifice 1 ef/wog/lod over not doing anything but standing still and channeling a spell for 16 seconds. another perspective: shamans have to spam LB for 15 seconds (6 casts) in order to get back 7.5% of their mana. druids would have to not heal for 16 seconds to get back 7.5% of their mana (10 sec + 6 sec).
pallies have it by far the best now, you don't actually lose any healing uptime at all. you just lose being able to use 1 spell every 18 seconds, all other healers have to actually stop doing what they're doing for a huge amount of time.
DP should be around 5% imo