well based on the equations in the wiki the healing power from your build (400) only gives you 50 hp a second more from regeneration and 400 hp more from your healing ripple (minor trait under the master tier in water). So the choice is yours there but i think generally think you need around 600-700 healing power to justify having any at all otherwise the dps sacrifice seems a little wasted.
I have done wvw in the past a little and know that it works a little differently to spvp however i think mist form is only really used as a safe stomp and is generally useless as anything else. In a 1 vs 1 i would only waste the cd if it meant my dodge roll in water attunement (with evasive arcana) would heal me enough to win the fight. However i think the stomping nature in wvw is not as vital in the sense that if you miss it you could lose. So for survivability i prefer arcane shield to mist form as it gives you the 3 blocks and the guaranteed crit at the end of it which is enough for you get the edge over a thief for instance. (basically use this skill offensively at melee range). Oh and its also a stun breaker so you get 3 of the best mechanics in one skill :p. But that depends on what you use mist form for. If you did take arcane shield you could swap out cantrip mastery for soothing wave.
the only reason i use inscription is for doing my world completion for perma swiftness however in a fight you will have perma swiftness without the heal glyph or inscription due to the elemental attunement combined with fresh air. i would consider IX or X in air as a trade off.
in terms of crit chance and crit damage i would try and keep your base crit chance at the 43% mark but increase your crit damage for more dps considering your most powerful attacks will be under the effects of arcane fury. If you took air training (X, air magic) instead of inscription then i think sacrificing some crit damage for vitality would be a decent trade off or even healing power. I think you will be better off with vitality rather than toughness as this gives you a longer time to cleanse conditions before they kill you and i suspect you are vulnerable to them with that build.
Have you tried signet of restoration? Its my preferred heal myself and you could substitute the might with runes of strength.
If you took the signet and 600 healing power this gives 262 (signet) + 205 (regeneration) + 110 (soothing mist)( pretty much permanent with lingering elements) = 577 hp a second, potentially.
When i was deciding my wvw build i used this site http://gw2buildcraft.com/calculator/ as it allows you to manually enter changes in stats to see the effects to regeneration for example as well as gives you your ‘effective hp’ which i can only assume is hp after armour is taken into account.
(so semi fresh air S/D ele)