I just finished shooting my 9c and my fs 40 side by side so I could compare them for you.

The grips I think are the same. With the changeable back straps they feel the same in my hands.

Shooting, I think the fs40 is actually a bit softer than the 9c. I was using 180gr ball in the 40 and 124gr Lawmen in the 9c. The fs40 is louder, but to me the recoil is less.

The 45 has a completely different feel, it's a different frame.

If you go with a fs40, you can always buy a S&W 9mm or .357 barrel for $65 and swap the gun to a different caliber. Just a thought.