You already have a beater, right, GP100
The M19 can cover more bases than the Trooper except one. A fast Bullseye match like PPC or Bianchi Cup where shooting has a par time.
M19 is better at IPSC & IDPA, police or security work, better at CCW..thinner & lighter, more people are looking to buy a M19 than a Trooper, M19 is eaiser to find speed loaders & holsters and it's about 100X eaiser to locate spare parts for any K frame vs Colt Revolver. Whoops...dropped it and now I need a new hammer & front sight. More gunsmiths can work on a S&W successfully vs a Colt. The M19 will handle faster.
So why the Colt?
Becaused you asked.
You are hooked on Revolver shooting. Admit it. And if you think you will stop wanting a M19 afterwards...forget it. You will and that's okay. Either way you can't go wrong. Phony-up and enjoy.