I would think this ring best for event fights. Like versus Maat, for some jobs. And also against HNMs, the mega spells that do thousands of damage don't apply, but typically HNMs hit hard and the +3/4 VIT rings for PLD or +3/4 AGI rings for NIN won't even be noticed, but +75 HP will help buffer those hits pretty well.
I would think this ring best for event fights. Like versus Maat, for some jobs.
You pretty much HAVE to have defeated maat to get this ring. LV85 NM drops it, so yeah. Most likely need a full alliance of 70-75's or atleast 9 75's >_> Very tough NM.
Barspells can increase resistance by up to 60-80 or more depending on your enhancing skill, so it is possible to balance it. And it also means that -Fire reistance isn't always going to ***** you, because it has about as much effect as a negative Barspell.