While Lifewarding is not a major enchant, and I expect Blade Warding will probably be a little more beneficial. I have been testing it.
To date I have not tested it much, but found the following.
Lifeward has been declared to have approx 10% crit chance. I will test more into this, but my first run with it seems to agree.
Lifewards is said to heal 350-380. I foundit often healed less then 200, but also sometimes over 400. 370 was the most often noticed proc. Over all I would say an average of 360 could be fair.
It had been altered in proc rates, had its amounts increased, and mats reduced. And over the course of 30 second trash fights often procced at least once. In a 90 second fight it game me around 2k (2056 exactly) healing, nearly same as a full stacked proc of blood draining. (on the final boss of Old Kingdoms).
Between all 4 bosses, it seemed to average about 1900. Seeing as i stayed above 70% the entire run, it proved more effective with passive heals then blood draining, which would not have procced once.
In a 5-6 minute long raid boss fight, i expect a much higher rate, ad will be testing this in naxx, uldaur and totc this week.
From a preliminary test I believe it should be alteast given the same point value as blood draining, or maybe sometimes close (10 or 12 point value).
Lifeward offers on average in a long fight 5-10k possible healing. This is a minor amount on a boss that can shafer health very fast like koralon or ignis put into time frames. On more stable fight like XT, kologorn, even this week raid Q ICC, it offered a stable 2-3k healing for each 10-15k damage done to me. My math may be bad but that is up to 20% more effective hp, the same as Blood Draining.
The mats on this enchant are now very cheap, and as effective as a top marked enchant.
I how ever prefer Blade warding, and enjoy accuracy more when my hit rating fails me. But I do think Blood Draining and Lifeward should be valued equally.
If you're at or above 70% hp a heal from a proc is not very valuable regaurdless of if it's 1k or 10k, you're in no danger of death unless the boss you are fighting can hit for 70% of your health. blood draining is very similar to ardent defender in the pally tree which is a saving grace on many ocassions, it gives you a heal when you really need it, not when you just need a little topping off.
Im glade to see someone trying things that others aren't. At the same time I still think bladewarding would be better not getting hit should be the tanks main thought for raiding. Healing is the healers job. But at the same time if that 1k or 2k healing saves you / stops a wipe then I cant say much about it.
Well while I'm sure many would swear by Bladeward or Blood Draining, I myself have used Lifeward to great effect on first my paladin and also now on my warrior as a tanking enchant. The benefits of other chants such as mongoose or exceptional agility are relatively pointless at higher level raids or well i should say not as important to me as the survivability offered by Lifeward. Just after WoTLK came out, I sat there with a shaman friend of mine and we enchanted several of these chants and he sat there healing himself while i struck him. I was getting procs of around 350-400 heals and 800 crits nearly every 5-10 seconds. This was not a lot but it is a decent amount and can really mean the difference in a raid especially a long fight where the healers may already be overtaxed by area of effect enemy attacks on all members of the raid as well as possible running low on mana. The amount of the proc has increased since. It has been the entire difference in several fights that I recall.. one in old kingdom against Prince Taldaram on my pally when he was down to 20%+ life left and all the other members of my 5 man heroic were down... Lifeward as well as some judicious use of seals and judgments and flash heals allowed me to basically solo him to death. I died a few scant moments later myself from a DoT but he went down first and so the group reaped the benefits. If beers were available over the web, they would of bought them that night. And most recently on my warrior when we were taking on Deathbringer Saurfang in 10 man ICC it made all the difference. After several wipes I ported to Dalaran, bought the mats and had it enchanted onto my mace by one of the raid members and it allowed the healers to focus more on the other members of the raid and the edge it presented was the deciding factor for us not to wipe (according to my healers, not me).
I'm not saying Lifeward is the best for every tank or every application, but I believe it deserves some credit as a tanking chant. say 12 points. I have literally had a group tell me they would not take me unless i had a wow-heroes approved chant on my weapon and that Lifeward has no score at all. This from a chant that has made my survivability noticeably better is I think just silly.