I did a thread a little while back on the Tungsten Guide Rod from glock store.com.
I had to return a first then a second that I tried in my GEN 4 G23. It seemed who ever tried it in this paticular gun had the same failure to feed issues I had. Its a great concept but poorly executed. After shooting my wifes gen4 G19 I decided the recoil wasnt bad enough compared to my G23 to focus on persuing it further. Besides you dont want to call a time out in a self defense situation because you bought an after market part!!
Lastly GSC was easy to work with on the returns and who knows, it may work for you!!!
I bought a SS from glockstore and did notice an improved muzzle weight difference with no problems. I have a G17 gen 3. I did read a lot of complaints from dual spring assemblies. Not many about single spring assemblies. Happy with stainless.