The Sig has the "traditional" double action. With a round in the tube and the hammer down, you have the heavier pull on the first shot as the hammer is retracted. The next shot has the light "single action" feel because the cycling slide has cocked the hammer for you. You need to be prepared for that "dual" feel. The Glock feels like a very light double action only for every shot.
Another Glock vs Sig issue: the chamber. Glock carves out a broader feed ramp that leaves some of the case head unsupported. This makes for very reliable feeding of factory ammo, BUT it causes the case head to swell slightly upon firing. The swelling makes the brass unfit for reloading. It also means that Glocks should not be fed reloaded brass that hasn't been "roll" resized to ensure uniform strength. Glock specifically recommends against using reloads. The Sig chamber is fully supported all the way around. Reloads aren't a problem. You can "correct" the Glock problem by installing a Jarvis barrel with full support for the case.
I find that I can shoot the Glock 23 or Sig 225 equally well. Some Glocks feel too "blocky" at the base of my fingers. Too bad you are stuck with 9mm. The steel silhouettes at my outdoor range drop every single time I hit them with the .40 S&W. The 9mm rounds only knock the silhouettes down when fired from the Ruger PC9. The same ammo fired from a handgun simply causes the targets to shudder a bit, but NEVER knocks them down.