Further update:
Finally got some time to take out the brake pads and inspect them. I have a great deal of experience with disc brakes from a professional automotive standpoint so I've attached some photos to help illustrate what I have found.
First things first. Semi metallic pads are always prone to noises. The metallic fibers are great for initial bite but are also the cause for many unwanted noises. Some times when the pads are formed groups of these fibers clump together or tend to break apart leaving a rough cratered surface when viewed super close. Unfortunately I don't have any macro lenses to illustrate this but the photos were taken with a decent high quality camera phone so zooming in can help some.
I found some instances of this cratering which is easily rectified by a light even sanding with fine sand paper over the surface.
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As you can see one of my rear brake pads has a severe groove. This was sanded down until the groove was not visible. There were no corresponding marks on the rotor face.
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This next part I think makes all the difference. Chamfering. So my pads are sanded smooth but if you look closely at the edges, they are rough and pitted. Again this is common with semi metallic pads. Best practice is to sand the edges lightly on and angle to smooth out all those rough spots. This will help further in preventing squeal noises.
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This may require some zooming to see the difference but after a light sanding of all the edges everything is completely smooth and ready to go back together.
Make sure to clean the rotors before reassembly while you have the calipers off.
This chamfering method is actually an approved warranty repair at BMWNA for brake squeal complaints. I find it works very well. Hope this helps anyone who is experiencing some brake noise issues and doesn't want to toss a nearly full brake pad.