The main factor was the cost.a If I had unlimited funds I would have probably had a fiberglass professionally installed. I priced every kit available pretty much. Also, since we are doing the install ourselves, I was not confident that I could get all of the angles, slopes, etc just right. I had a deep end with an expandable liner in my former pool but it wasn't perfect and I decided that if I just stuck with a 54" deep flat bottom I could get it pretty close to perfect.