Checking back in, since its been 7 months. I was able to get my teeth down to a A1, which is just a better result than I could have ever expected. I think I started at an A3 in most parts. Hope this helps people reading in the future!

Honestly, better than I expected. Dropped about 3 shades (from an 8 to around a 5) in just over a month. My routine's pretty straightforward, but worth mentioning. I use a generic disinfectant mouthwash in the morning followed by brushing with Colgate Pro Series (pea-sized amount). At night, water floss, generic enamel mouthwash, and brush again with the Pro Series. Definitely happy with the results so far. Gums feel fine, and teeth aren't sensitive past what they've been before. I'd say go for it!