Is Health Regen % Meaningful?

These items.
As the name 'Phoenix', the less health you have, the more (amount of) health regen you get. This is how health regen % works.

...but are these stats even meaningful?
I tested the % health regen with this item:



I self-injured hard and wore it. I got about 3k~4k regen on the first tick.

Even with the +2000% regen, it is hard to use.
So I ask... if there's the % health regen build(But without that necklace), will it survive well?

 

It's really good at almost-dead moment with the phoeniex crown it heal me for like 100-200 hp when i almost ded

(dead english in the morning)

 

Nope. I get 2-4k from the necklace, so that was almost COMPLETELY the necklace

 

Yeah necklace is the only useful thing when u want %health regen

 

Yeah just carry it around and slap it on between fights, boom far fewer potions necessary