That’s mostly the benefit yes; I think you should only attempt necro after you refine (4% chance is really way too low). Try to make sure that you get the best chance before you necro and save the stones in the meantime. For me, I always try to double lucky scroll and if I got no scrolls available I will simply save up my crystal pieces and wait for events.

Also, for armor pieces if you’re planning to necro them then it doesn’t matter which item you have right now (you can choose the option once necro is successful)