I just installed one on my Glock 27. Haven't fired it yet, but I sure will once the weather breaks. The trigger is a little fatter too... feels nice.
I don't carry my Glock chambered, but now I may since I have that little extra confidence of safety. To me I'd rather be 'fumbling' trying to push the siderlock button than chambering a round in a stress situation...
To each is own for sure.