I do this all the time. I always have NF yogurt on hand and I never have sour cream (NF or otherwise). Plus, if I buy NF or LF sour cream for a recipe that uses only 2 tbsp, the rest of it is going to sit in the fridge and go bad, whereas I eat NF yogurt every day.
I use greek style yogurt, which is already strained, so I don't have to deal with straining it. I also like the taste much better than regular NF yogurt (I can barely eat regular NF yogurt anymore). I don't taste the difference with the Greek-style yogurt, although it's been so long since I ate sour cream that I'm not sure I'm reliable on this. But I can definitely taste the difference with regular NF yogurt.
1 tbsp of fat free sour cream is around 10 calories, 1 tbsp of Trader Joe's Fat-Free Greek-Style yogurt is about 6 calories. So it's more a matter of convenience for me than the calories.
My Before and After Pics
"Decide what you want; decide what you're willing to exchange for it; establish your priorities, and go to work." --H.L. Hunt
"Life has hills. Set the treadmill at an incline."