there's no point rly, basically in almost every cata u need a healer, and without a good gear 10k life (so let's say 2-3 "lives" of a normal pala) wouldn't be enough, well, in some cases it might tank enough to avoid healing but u'd be better off dealing more dmg and also u might struggle at eps/quests
and if u have a healer in ur group there is rly little difference between 10k and 4k life, unless it's a quest that deals massive dmg, but anyway sooner or later the group will die if the healer isn't able to heal the damage the ep deals, it might just give the healer a few more seconds to realise he needs to start healing, that's a massive loss of dmg throughout the climb tho and i don't think its worth that

If you can't do damage, it won't matter how much HP you have in my opinion.

Sure, some people can do 2x the average of others, so they might make up for your lack of damage, but overall it's best to just get good tanking/healing gear on Paladin with a halfway decent EE weapon. Maybe throw some int/hm on the weapon too to help your heals, but your primary role should be tanker, up front, with an acc heal charm just to help aid the main healer.

For soloing, this would be super slow, your damage is nil so trying to kill an EP would take an hour, let alone three of them.

It's a fun build no doubt, but it's not exactly functional unless you get "carried" and that's not that much fun.