There was a thread about closed loop steppers a few months ago with lots of discussion.
From my perspective it is of limited use. The closed loop may give you signal that you lost steps but if you overload the stepper(e.g. too much acceleration of other forces) then it will just stall, closed loop or not. Unlike servos the closed loop driver will not increase torque to make good for it (as far as I know) it will just try to repeat the missed steps. But my knowledge may be outdated here.
And, as you mention, 282 in-oz may be a little on the low side for your heavy spindle and the mid-size machine. At least if you want to run it at reasonable speed.
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