I had a pretty big difference between broadhead flight and field point flight with my old bow. It was tuned as good as it was going to be tuned, and it grouped very well. But I still had to adjust my sight to fit my broadheads, and different broad heads flew a little differently.
I had always heard that a perfectly tuned bow would shoot a broad head just like a field tip, and I never really believed it. Then I got a new bow, and that changed my mind. I had previously shot a cheaper, lower grade bow. It was a great bow, but it was inexpensive, and we all know that to a point, you get what you pay for. My new bow is a higher end bow, the best I could afford. The difference is like night and day. Right from the bow shop I came home and started shooting perfect groups at 40 yards with my fixed blade heads. Better yet, my arrows flew exactly like my field tips. I practiced all summer out to 60 yards and never once had to adjust my sight, no matter what heads I had on my arrows. I shot a couple different kinds of fixed blades, muzzy MX3, MX4, and G5 montecs, field tips, and some mechanicals, and they all shoot exactly the same out of my bow.
So with the right set up, you definitely can get the same impact with different types of heads on your arrows. some set ups, you will just need to adjust your sight. All you can do is make sure your bow is tuned up, see how it shoots, and make sure your pins are set for your broad heads.