I have a 9mm Sigma and my only real concern about all these people wanting to lighten up the trigger, especially first time handgun owners, is that this gun was designed to be a service weapon, NOT a target pistol. It was not designed to be shot for hours on end. Of course your index finger and arms will get tired with a pull this heavy after extended use.
When you modify a gun away from spec, don't be surprised when you don't get the satisfactory results. Even Wolff tells you, "Warning: For competition use only - not for duty use." That should be a major tipoff! In other words, if you fall off that rock and break your leg, don't come running to me!
Don't get me wrong, I can certainly appreciate the appeal of a genuine Smith & Wesson pistol for $300.00, but don't make it into something it is not. This gun has been out for awhile and there are plenty of reviews out there so there is no excuse for not knowing what you are getting into. The trigger pull issue is well known, but yet, you (whoever you are) bought one anyway!
OK, so lets assume you knew nothing about the gun before you bought it, why would you keep it if you found it tiresome to use because of the trigger pull? I understand that you own it and now you want to try and make it work better. I get that. With this mod, however, you are not necessarily making the pistol better. If you are lucky and shoot the right ammo, you will have a much more comfortable gun to fire, but don't come back here complaining about misfires.
In my opinion, life is too short to shoot something that you don't like to use. Why not just sell or trade the Sigma and take your lumps. Most major dealers are sold out on this model so you should have not problem getting rid of it.
After you do that, promise yourself that you will do a better job of researching your next purchase BEFORE you lay your cash on the counter. Better yet, see if there is a range that rents guns. That way you can "test drive" a variety of weapons without having to make a long term commitment. Or if you are not shy, see what others are shooting the next time you go to the range and ask to shoot a couple of rounds. Using one or all of these methods, there is no excuse for owning a weapon that does not suit your needs.
[/RANT] off
OK, I will get down off my soapbox... for now!
Happy Shooting!
Scott