I personally never used grenades on my nm trials runs but they sure look helpful especially early game.
I did use resistance tonics though quite often to reduce some damage at least when wearing pact belts.
And I tried the confuse grenade tactic once against gurd just to see the cheese.
Bottom line they are great to speed up killing stuff given that you really don't want to stealth / scirmisher forever with a rogue or fade step doubt stealth constantly with a mage because that's annoying to kill one promoted Mook over 3+ minutes.
Lol riight but yeah it's a huge help early on I kinda don't use it once going to Skyhold besides them spirit tonics for them god awful promoted wraiths, I'm going to try to limit the use of them with this assassin run to enemies that fall under the same as them un killable barrier mages.
Was also thinking about just using stock bombs and tonics this time to see if it was a bit harder. And lol gurd wow I literally could not beat him with them confusing grenades but there I felt like I cheated I must have died two hours straight on stream lol one of my 3hour long streams was trying to beat him I got lucky with them confusion grenades, can't believe you did it with a necro that is super impressive my friend, my rift Mage got whooped up, I wonder if my assassin can even make it that far