Well!
To answer your question, I do just fine as an EK after the vocation balance (654 EK)
To narrow my answer down a bit, there are times when it's necessary to use it, and times when you should take caution (In other words know your limits)
I'll explain to you how it works for me:
When I'm solo hunting, let's say for example: Summer Court.
I've been to this spawn HUNDREDS of times solo, so I already have an idea of what these monsters are capable of damaging.
I can full box, with utito tempo my entire hunt. But I can also do that because of my fire resistant equipment, physical protection, life leech imbuements, void imbuements, and amount of HP I have (9875).
Now because of all of these things, I can comfortably use utito tempo without spamming supreme health potions, and rather use exura med ico and throw that into my spell rotation after every attack spell.
Now let's say I didn't have any of those imbuements, or fire resistance, all I had was a basic set, and my HP alone.
I would get recked.
Imbuements play a big part in counteracting with utito. You're soaking 15% more damage but you're still benefiting the bonus of imbuement. If you can't afford imbuements or nice(r) equipment, I would take caution on using the spell.
Now let's say we're in a team hunt, we're in cobra basement -1.
It's safe to say we all have a rough idea or know exactly what kind of damage output they have.
Now you're full boxing monsters that can combo you for 1000+/- give or take, and you're full boxed. Is it safe to use utito tempo?
Can your druid heal you enough? Can you rely on him?
Try a few laps out without utito, and see how low your HP drops. In some situations, I won't lie, I'm scared to use utito because of the druid I'm with. They panic, they don't have experience with the spawn, or they focus mainly on their waves/aoe damage, and that leads me to use supremes while I'm hunting with them. Other times (now I have a set team), I go with an experienced druid and use utito without even having to use any supremes, because with the first few laps I ran around the spawn with, I noticed my HP didn't drop below yellow. If you're still unsure at that point, use utito when you're not full boxed, or when the box around you has low red HP, so you can utito + exori gran and make the finishing blows.
It's really all on how comfortable you are how well you know whatever you're hunting.
I hope this helps you,
Cheers!
Jay :)