My water is like liquid rock, with a pH of 8.0, and my bettas are fine. They really don't seem to be sensitive to this stuff as long as you acclimate slowly. They live in some varied situations in the wild, and generally adapt well.
As far IAL goes, that doesn't really help enough to make a difference, and you're back at square one every time you do a water change. I think you will be OK as long as you introduce your new fish slowly. If you do planted, your plants will like the minerals in the water as well, which will reduce them a bit.
1 - 55 gallon planted community
3 - 10 to 20 gallon planted betta tanks
My advice: slow down, think, and be willing to learn. Then you'll be fine, no matter what.