You can't have content scale different for each tank. Right now, WAR is almost perfectly balanced with PLD for 4 man content, and *well* behind PLD on 8 man content. Your changes, since they are just flat increases rather than changes to scale, would make WAR better than PLD for 4 man content and *still* worse than PLD for 8 man content. Basically, unless you actually change how the WAR self healing scales, WAR will simply be the 4 man tank while PLD becomes the 8 man tank, which still has WAR getting excluded from all real end game content.
This is the problem with *every* suggestion by people that look at WAR, hear about how it's worse than PLD, and end up thinking that increasing self-healing is some kind of a WAR performance panacea. It's completely ignorant of the actual reasons that WAR has problems.
It's also important to keep in mind that self-healing is naturally inferior to straight up mitigation: WAR has to *survive* a hit to heal itself back up; PLD just takes less damage. So, for the big burst damage mechanics that the devs are so fond of, WAR becomes *way* more likely than a PLD to die because, while a PLD blows a CD and just takes less damage from the hit, the WAR has to survive the hit so that it can mitigate it after the fact. Because of *this*, the more of your mitigation that is derived from self-healing *the less effective of a tank you end up being*. Self-healing as a secondary mitigation mechanism works just fine but it can *never* be a significant portion of your total mitigation if you want said tank to actually be able to do upper level content. There's a reason why pretty much *every* self-healing-as-mitigation tank in games gets changed to rely less and less upon that self healing (either that or the devs just stop caring about balance altogether, like what happened in City of Heroes with Regeneration) and more and more upon properly scaling proactive mitigation mechanisms, like absorb shields that scale off of damage taken over the last X seconds and static damage reduction: you can't balance effectively across multiple styles of content (PvP, small group, large group) without doing so.
Also, the Holmgang change still doesn't do much to make it useful. Holmgang's problem isn't just in the fact that it binds you (which, btw, is likely the intended purpose: to make you immune to knockback and forced movement effects; Holmgang is supposed to be the WAR version of Tempered Will); it's also the fact that it's got a 6 second duration on a 180 second CD. Even if it *did* provide a massive mitigation buff while active, it still wouldn't do much because its got absolutely crappy uptime (3.33%). The only CD in the game with a *worse* uptime is Hallowed Ground (2.4%) and that's for a pretty obvious reason.