Rednose I use to run a two piece (cut collar/vest) as well. After I lost a real nice little catch dog because he took a perfect shot between the two, I quit. I also think it’s too much. I run my garmin under the vest instead outside of it. Having the cut collar built onto the vest makes that much easier and eliminates the chance of that lucky seem shot. I have watched my dogs flex in the two piece rig and TO ME, the one pice set up just allows more flexibility. As said though, no right or wrong just personal preference.
Yeah I'm not sure on the two piece setup as I have only ran one piece vests but one had an actual chest plate one does not. The one that doesn't he moves much better in and is far lighter though it has two layers of kevlar more. This is why I like it the best of what I have seen. I would like the taper you drew though.