I have exactly that set sans UVs and honestly it's only so-so. i'll start from the top.

Status resists like fire freeze shock poison are equivalent with very high status resist UVs, but damage resist UVs like normal shadow piercing elemental are more like very high = ~1/5 of a 5* item's defense. Status resists are also not 50% preventaion like you're thinking, you aren't immune to a status with 2 resistances it just gets progressively less likely and when it does happen the duration and severity of the effects are weaker. You can still curse yourself with a grand faust while wearing this set it just happens about a third less and the curse never hit more than 2 items or lasted more than 15-20 seconds from what I can tell but I didn't exactly do extensive testing with that, i only have the normal faust and i don't use it often and I only charged up a couple dozen times in a terminal to see if i was really immune or not.

In general the set works fine in most t3 strata that aren't fsc, which sucks because the medium damage boosts to fiend/undead would be great there but the prevalence of normal damage from rolling traps and trojans and the duke can very quickly paste you. Also despite what the wiki says t3 is far from pure damage attacks. No one has knuckled down to really figure out the exact numbers to my knowledge but just about everything but puppy bullets does at least a little normal damage and any elementally themed enemies do some elemental damage, so like a shock or fire devilite hits almost as hard as when I'm wearing normal/elemental armor despite my huge shadow defense. The slew of resists is nice, you're still going to want to keep a stack of remedy capsules to stop status effects in t3 though, even with reductions you can't afford to lose a third of your life to waiting for fire to go out or risk getting caught unshielded again as you take a shock tick.
The dragon scale shield is actually really good, when it comes to pure damage ranged attacks like gunpuppies projectiles or polyps or jelly spikes I'd say it's even better than the grey owlite. Something that's a normal ele mix like a mecha knight spin the owlite is still your man and despite the piercing defense you still can't shoulder something like an alpha wolver onslaught but it's an all around excellent shield in t3.
You can also do t2 or t1 fine despite the lack of normal defense, at least I never felt underpowered probably because just the raw health you get from any 5 star set will carry you through easier content. More and more i think for t3 you're best off making a different set for every damage type if not every strata, in which case swapping the radiant for valkyrie and the dragon scale for a crest of almire or skelly would make a more ideal anti shadow damage/fiend set.