The Kimber 84M's rise in popularity was mostly due to the chase to find a 5lb. hunting rifle at a reasonable price. I have a couple 84Ms and a 8400. If I were climbing sheep mountains, I'd have no problems reaching for a Kimber Montana 84M in .308.
But me, I keep my rifle slung 95% of the time so the extra weight and 5" inches of added length of the 8400 doesn't bother me.
And, yes, to me, the 8400 just fits better. It's a much bigger rifle and the added heft is something that feels more natural and comfortable in my hands.
I find myself in the mountains of Colorado or New Mexico each year when I'm lucky and as much as I like the fit and feel of my Kimbers
I only have two centerfires......an 84M Classic 7-08 and Montana in 280AI
I find a Remington in my hands more and more each year.
The extra heft feels good to me as well.
Ted