This is just my opinion, so take it for what it's worth. I don't think there would be a measurable difference based on the flexing. If your arrows are spined right for your bow, they should be going pretty straight when they impact the target, so they will penetrate as well as your broadhead design allows.
If you increase the arrow spine, but add point weight, you are right back where you were in terms of spine. More weight up front effectively reduces the (dynamic) spine. That said, your arrow may very well penetrate better due to the increased overall mass coupled with the higher FOC. The static spine will have a rather insignificant effect compared to the mass/FOC.
That's my opinion anyhow, your mileage may vary.