Most balun/extender mfgrs. state that use of EZ connectors is not recommended or supported. They end up being forbidden at any company I work for. Whenever I see them I think to myself, "I bet those were made for electricians trying to do LV".

I've been using one-piece RJ-45 connectors since I started & they're cake for me. I bet my rate of crimping a bad connection is less than 1 in 250, and that's being conservative.