...but remember, the stock trigger DOES tend to improve significantly with some wearing in. Sometimes in as little as a few hundred shots.
Wifey's Shadow has the old GTX in it, and compared to the new Shadow I bought recently (for conversion to .22) it is a zillion times better. But compared to my 3 year old Shadow, well... it's better, but the difference isn't as great.
The similar trigger in my B19 had a really nice, light touch to it - it was far and away the best Theoben-type trigger on any of my rifles.
Then, one day, it wouldn't cock.
Turns out that the factory slop in the trigger, combined with wear, meant that the sear was not sitting directly over the piece that's supposed to block it. Rather, it was off to the side - close to the edge - and as soon as the trigger started to move the blocking piece during the "second stage", it just kinda slipped off and the gun would fire. Eventually the edges rounded off, and the sear wouldn't stay blocked in the "up" position (hence the refusal to cock)
I fixed it by stick-welding some material to that little blocking piece and grinding it down, so that it was a little thicker in one area. This keeps it centered and functional.