Well, personally, I wouldn't use any case for my iPhone that was not on the Apple site. But that's just me. I'm sure there are tons of people who use other types of cases with no ill effects.
Right now, I'm putting my iPhones into a double-sleeve case, but that's because I like the feel of the "naked" phone, and I like to see the beautiful back! 🙂
So, I'm not an expert on cases. When I used to use one, I only had a bumper on it (that I purchased through Apple). Hopefully someone with more experience with actual cases may see this post and chime in.
Sorry I couldn't be of more assistance!
Best of luck,
GB