Note: I'm afraid that this question might make some cessationist readers uncomfortable, but given that Latter-day Saints are continuationists, I'll just go ahead with it.
It's my understanding that Latter-day Saints consider themselves in some sense "special" with respect to the rest of Christendom. For example, this answer affirms (emphasis mine):
[...] only those who are baptized and confirmed as members of the Church of Jesus Christ of Latter-day Saints can receive the Gift of the Holy Ghost. Once they have received the Gift, they must live worthy of it in order to maintain the constant companionship of the Holy Ghost.
Those who are not baptized can still experience some of the Power of the Holy Ghost, receive certain Revelations, and feel the influence of the Light of Christ, but they do not have the promise of constant companionship from the Holy Ghost.
Additionally, receiving the Gift of the Holy Ghost naturally grants greater access to the Gifts of the Spirit, such as the Spirit of Revelation and many other gifts.
The quote above is essentially stating a factual prediction about non-LDS Christians: non-LDS Christians cannot have a constant companionship from the Holy Ghost and, therefore, shouldn't be able to access greater manifestations of the gifts of the Spirit.
I've watched and read lots of testimonies, as well as stories of moves of the Spirit in different revivals throughout history, and cannot help but believe that this prediction is utterly false. There are tons of non-LDS Christians who can testify about how they have been led by the Holy Spirit pretty much everyday, how they operate in the gifts of the Spirit -- including "words of knowledge", which would be the equivalent to the LDS concept of "Spirit of Revelation" --, stories of people who were involved in witchcraft, the occult, etc, who had first-hand knowledge of the dark side, and then had dramatic supernatural conversions to (non-LDS) Christianity and are now having even more profound experiences with the Spirit of God.
Question: How do Latter-day Saints explain testimonies of profound experiences with the Holy Spirit in other denominations?
- According to LDS, do all non-LDS Christians lack the Gift of the Holy Ghost, and if so, how does this lack manifest itself in the lives of non-LDS?
- According to Latter-day Saints, are all Christians who are full of the Holy Spirit unequivocally led by the Spirit to accept the truth of Mormonism?
- Do LDS believers not accept any others who self-identify as 'Christian'?