I"ve run it for competition - in my particular situation, the trainer I hired disappeared off the planet at 10-8 weeks out when I was switching from my bulker phase and left me at a point where I really had no other option but to go ultra aggressively to hit my contest date. Dave's diet got me there for sure, but I gave up mass and by the time I got on stage everyone was telling me I looked wiped out. I was doing much more cardio than normal and very aggressively on the restricted calories.
If you follow it w/ reasonable calories you will definitely see results and I don't believe you will give up much mass. You will be flat while you're on the keto phase and the refeeds take a day or two to process. I personally found the diet very easy to follow as I do well w/ very simple and repetitive diets, and I also liked that I didn't feel full or bloated. My body doesn't like fat loads or carb loads so it was a nice balance for me.
Give it a shot. As long as your protein is sufficient, the fats are sufficient and you don't go crazy w/ the cardio, it will work. A warning on coming out of a keto diet however - introduce the carbs back in slowing to a maintenance level. So you might see your bodyweight go up a bit while it adjusts to supporting more carbs that it was used to processing.
An alternative is a carb cycle. I've also had excellent results from carb cycling.