Last year there was a two week window where I did Keto. It was cool, I did have the Keto flu symptoms. I lost about 8lbs in a week.
I think the cons were the flu and the weak symptoms, the pros were I had no desire for carbs/sugar. Even with loosing over 100lbs with IF I would still indulge sometimes. Keto requires less wiggle room.
Overall I don't think I will try it again. I saw massive weight loss results with just IF, plenty of water, exercise, and eating the right things. Keto is dope if you can sustain it but its a reason keto is a DIET and IF is a lifestyle. Also when I did keto, I was still doing IF and that's important.
If you combine IF with keto from my own results you will see massive quick results. Its not water weight, you're loosing a LOT of fat. I would venture to think if you did keto/IF together for two weeks, you could probably loose 10-20lbs, once you hit ketosis with the eating intervals along with exercise equals fast results.
With my whole journey with IF, I have been able to sustain and keep the weight off for the most part by simply sticking to the IF regimen everyday.