So you got me thinking Hipps about overlapping frequencies today so I tried a little experiment.
I returned my crossovers to where they were when I was running a 2-way setup and then crossed over my mids in the range where the mids play flat, 330 - 5k with no regard to other speaker crossovers points. I have to say, I was VERY pleased with the result. The sound in itself did not change but it improved the imaging considerably while maintaining the forward stage.
After bouncing back and fourth from my original "Golden" config to this new config a few times, overlapping wins and will remain.
I believe this to be a result of the distance between the mid-bass in the doors and the mids in the dash. Turning the mids into "complimentary" speakers seems to me to be a very nice solution for anyone dash mounting mids in the factory location.
Ps. You might be thinking, why not run all speakers in the range where they run flat, I tried that because I had to know! Blah! Not recommended but it was a good lesson.