A-body vs fmj spindle for handling?

I don't know about 3 pounds, but I do recall the FMJ spindles being lighter to the point that it's noticeable if you pick one up.

Is this 3 pounds for EACH spindle, or for the pair of them, for total weight?
Is 3 pounds really gonna make, any kind of difference, in the real world of things?
After all, your not designing brakes for the next generation Martian land rover.