The GR features a connector and overtravel limiter. You fit it to your gun and are good to go from that point on. If you over-file it they will replace it for free.
The LWD-UTS is based on the trigger housing. It features an adjustment screw that allows you infinite adjustment. It can be turned on or off and installed gun to gun. You can use the connector you have or purchase another.
Neither one is any more reliable over the other. We have thousands of happy campers using both. FYI: Anybody that tells you a UTS set screw can move out of place is selling snake oil. If you ever adjusted one of these you would know for sure and call BS right from the start.
Neither of these will address pre-travel. Adjusting PT is a bad idea because you will be eliminating the trigger safety and firing pin safety. These two safety's are in place to keep you from doing something stupid.
The stock striker spring and trigger spring are both 5lbs. You can go to a 6 lb trigger spring. It helps pull the trigger reward with less effort. You can go to a 4 lb striker spring. This offers less resistance during trigger pull. Installing either of these (or both together) result in the finest trigger possible HOWEVER they can also result in FTF. So.... once you have them in your gun you need to prove it (reliable) by firing several hundred rounds.
See the LWD-UTS here http://www.lonewolfdist.com/Search.a...timate%20trigg