...want to know what the advantages/disadvantages are to having smooth grips.
One disadvantage to having rough checkering on the grips is in shooting magnum lightweight revolvers with high recoil, like the Sc frame &/or Ti cylinder models. They just eat your hand up.
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Here's my 642 before I took them off. This boot style has a bulge on the right half, which caused the front sight to be off by about 1/8 inch to the left within the sight radius when point shooting. Not good for a CCW.
I was told when I bought my 640 that it came with Badger grips, so I can't be 100% sure, but they look nice!