Check the mod priority guide:
https://docs.google.com/spreadsheets/d/1ty239kyJbBs1sLhTo1JvSWuN0mIJsK1nwVdI6OLLtXo/view?rm=minimalPoincaré Recurrence brought with it a really solid set of upgrades. XM3, while the least important of that batch overall, is still a great MOD. Her overall desirability does depend on the prevalence of night battles at any given time, but for those night battles, she has a unique niche.
Her new Skill 2,
White Ghost, makes her first shot against an enemy during Skill 1 to be surehit and deal increased Crit Damage (the bonus Crit Damage is only at night, but you’re only using her at night to begin with anyway). Combined with her updated Skill 1 which has her prioritize targeting the lowest HP enemy, she becomes very effective at mopping up the weaker and potentially more evasive enemies at night, the kind that RFs can sometimes struggle to deal with.
Other nice bonuses she gets are a substantial Damage stat boost, but also notably a reduction in her Skill 1 ICD to 6 seconds. She previously suffered with a 8 second ICD, but she’s now in line with other standard RFs. Overall a solid upgrade, but her value is highly dependent on whether or not the meta of the week revolves around night combat.
MOD2 is the ideal upgrade point, but MOD3 does come with a nice Special Equipment.