Unless you're already Mormon I'd give that notion some serious thought. I was raised there as a non-Mormon and what you see on the surface isn't the reality.
I spend 8 years in SLC when I was a kid.
Concur with what you caution.
Of course, I didn't make it a point of telling them how they were all in a cult, were going to hell, etc. We worked together on common interests. So maybe that's your difference.
Most people tend to behave fairly decently, if you treat them decently. There are certain exceptions. Like those of a certain ethnicity and political persuation in East Los Angeles I spent a little more than a year living near.