Although this is Coach Eric's thread, I'll chime in with something very similar to Nathan's stroke I do with my masters group that works very well. I call it the "high switch", near straight arm recovery, fingers point to sky, and heavy swing arm slices in forward of head.
Introducing the leading elbow recovery can lead to tense shoulders and tense neck, swimmers are trying to muscle the position. When the swimmer swings high, the shoulder naturally opens and relaxes and momentum of recovery arm slicing in, swimmers feel the weight shift and connection to big muscles of the core (lats). Notice if Nathan's forearm would relax a bit, the high elbow position would remain in same position.
What I have my squad do is start with high switch for four strokes, then begin to relax forearm for next four strokes while holding the high elbow, then relax forearm until they drag fingertips for last four stokes still maintaining the high, wide elbow recovery.
The "high switch" focus/drill is almost identical to Nathan's stroke.