I haven't, but I certainly think you'd be better eating real foods than meal replacements. Also Keto is great because you are naturally less hungry after you have been on it for a little while. You need to eat calories though in the form of real fats such as butter and cream etc and protein while keeping carbs low so if you have been on a very low calorie meal replacement diet you may find it odd at first and against what you have been doing previously, but I believe if you change and stick with it, you will feel the benefits.

I haven't; but like @chinatowninchina, I would expect the benefits to come in after sticking to it for a while. It is possible that there may be some weight gain as you switch to more food and learning the types of fat that work for you; but overall, the positive impact I expect will outweigh the initial shock