Metal god, SOP for us was to keep the rear BUIS folded down unless your M-68 failed, then raise it up. That kept it out of the FOV until needed. Now as for the front sight, I didn't even notice it unless I was shooting or verifying the BUIS.
As for magnified optics, if you had it on a QD mount, you could remove it quickly should it become disabled.
Another option, should you have rail up front and not an A post frame, would be the offset BUIS. I've seen a couple rifles so equipped when using magnified optics. Optic fails, a slight 45 degree roll counterclockwise, and viola, BUIS. I've not actually shot that setup to see how I'd like it, but it seems good.
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Active Duty USAF 1994-Current