Well... sometimes KJV Onlyism reminds me of the man who draws water from an old well in a leaky bucket and runs home in the hope enough will be left.
To put it another way, fair and robust argumentation won't get any traction when hardline bias colours judgement.
But perhaps the worst impact of this unfortunate rumpus is how it directly insults those sincere believers who grow in the knowledge of Christ through reading and studying their "modern" translations.
Over the decades it's this incontrovertible truth that has bothered me most. Along with many others, I've been using the NKJV, NASB, Amplified Bible and ESV for many years. They have helped lead me into a much deeper understanding of true doctrine and how to apply the fullness of it to my life.
These translations have often strengthened my relationship with God, encouraging true spiritual growth and correcting many of my failings. They have glorified Christ and given Him His proper place as the eternal One in Whom all the fullness of diety dwells.
They have taught me much about true Christ-likeness and the deceitfulness of the flesh. They have enabled me to recognise false teaching and the implications of deceptive half-truths that cause so much damage in the true Church. And so on...
In actual practice then, my appreciation of what God's living Word means to me is not in any way harmed or held back by using these translations (see personal essays below which hopefully will confirm this?).
So in the real world, using the KJV—or indeed modern editions/translations of it!—offers no worthwhile advantages over quality "modern" translations. While that's the kindest way to put it, we can't ignore the reasons why it's definitely not the ideal go-to translation today.
Walking Faith