I generally do a lot of sour mashing since I learned how. Upstate NY has pretty good water for hitting target ph, but I still do it anyways. I always do a sour mash with any recipe requiring wheat. I think it can really mellow the tartness of wheat and still not be sour-sour. Manhattan judges never detected any lactic acid traits in my beer. I don't want it do be too sour but it does take a little off the edge of the tart wheat flavor. From several books, sour mashing was popular for acidifying a mash.
If it helps, what I do, depending on the grain bill and style, I like to do a 5% minimash 1-3 days before the main mash depending on if I want sour or just acid. Mash the 5% as usual then rest to 90 degrees, pitch about 2oz of unmashed grain on top, put lid back on overnight. One person in my club said he did it in a kettle and put 4 brewbelts on it. My acidity tests show 1lb after 1 day usually makes 5.0. (store spring water here is 5.5) Next day prepare the full grain bill and add the acid mash to the grains and water, then mash the whole thing. There isn't enough contact time for a new fermentation on the big mash and boiling is going to take care of the critters.
My lambics & sours I do 20% for 2-3 days and still pitch WY3278 or High grav and IMHO, sour mashing is a very good way of acidifying a mash and is more controllable than some think.