Since there’s no caffeine, the main concern is the dangerous mould toxin, ochratoxin A, that’s talked about in this article: Safer coffee. Like it says, it can be toxic to the kidneys and potentially carciogenic, much like the aflatoxins in peanuts. It won’t affect candida, but it’s not going to do you any favours, so I guess it’s up to you.
Coffee, colon function and colorectal cancer was published a few days ago and shows the positive side of coffee. I’m pretty sure everyone here can attest to coffee’s “regulating” effects, something that shouldn’t be underestimated given what some members post here, and since it contains a lot of fibre and stool is 60%+ bacteria, it may suggest prebiotic properties. It’s also a powerful antioxidant and recent studies have shown it can help regulate glucose metabolism and lower risk of diabetes. A study I saw recently showed women with recurrent yeast infections had impaired glucose metabolism. In any case, there’s just as strong an argument for decaf as against I’d say.