I have both and each has features that are better than the other to me.
I got the SG first and love that the cable disconnects from the unit,I have cables in my Tundra and Sprinter and can easily move the SG as needed between them.
It could not be much more simple to use though and mounting is just a Velcro strip anywhere I want it to be.
The display is unreadable maybe 60% of the time now though and that sucks in any color I try,it is just old now and mine does not seem to read transmission temp at least I have never been able to get it o?
The UG is a work of art design wise at first compared to the SG mostly for the legible screen and options for designing the pages.
Upon further use though it was clearly designed by some moron it seems as the buttons are on the back which pretty much rules out many mounting options that I could use if they were on the front????
I simply can not understand the reasoning for this?
So I have a single page in use and I still get a lot more out of this than the SG in the end.
I will be ordering a WiFi model myself soon I am sure.
I like the buttons on the back of the UG, keeps the face night and clean. There are three buttons, enter, up/down. Doesn't get munch simpler than that.
If you use Velcro you can mount it to the dash and then pull it off when you want to use the buttons, which you shouldn't use while driving anyway.
Also you can change the color of the screen with different color clear plastic placed over the screen.