If the Christ within is any different from the Christ without then …‘Houston, we have a problem!’
Christ is the same today, yesterday and forever. What mystics experience are facets of Christ Jesus and in doing so help us to understand Christ in His humanity and Divinity and the Truine God. Always what the mystics experience by the grace of God is in accordance with the Gospel and Catholic Tradition, it has just not previously been enlightened by the Holy Spirit.
To say we do not need mysticism is to undermine the whole Gospel and Catholic Tradition, St Paul was a mystic, St Peter was a mystic (saw visions) our late Pontiff Pope John Paul II was a mystic.
All Catholics are mystics to some extent, participating in the mystery of Christ Jesus. To shun it, is a contradiction in terms.
God Bless you and much love and peace to you