I could be wrong here, but I'm pretty sure Lactobacillus delbrueckii, subsp. bulgaricus isn't an acidifier at all. It's a ripening culture to works on texture and aroma. Thermophilus isn't the best acidifier in the world, which is why it's normally mixed with a meso, unless it's the same strain as in TA061, which is't half bad. Bottom line, I am guessing, if it works for you go with it.