Sorry to learn the connector is failing in your Gen4. I would like to see this myself? Any chance I can get you to mail it back to me? I need to figure out what the heck happened? FYI: I have not heard of any issues with Gen3 pistols. This is the first failure I have heard of with the Gen4. Are you sure the connector was completely seated in the trigger housing?
The difference between the 3.5 and 5 lb connectors is the angle of the raised angled edge. Thickness is not a factor.