One tricky thing is the pH doesn't matter as much as alkalinity. Alkalinity is the buffering capacity. So it's like the difference between a dump truck and a VW beetle. They can both go 50mph but one is going to have to push a lot harder to get there.
In the same way water with high alkalinity will tend to push your mash to a higher pH than water with a lower alkalinity, regardless of the initial water pH. When I was in Missouri I had a well with off the charts alkalinity but the pH was normal.
I love my little KH titration kit, takes most of the guesswork out of it.