I used Maharishi Amrit Kalash for about four months several years ago. Since then I have used it occasionally from time to time.
I had an absolutely amazing experience. I am a practitioner of Transcendental Meditation taught by Maharishi Mahesh Yogi and I had heard a lot about how good it is for your health. So this is why I started taking it.
I found that after about two months of taking both MAK4 and MAK 5 as recommended (take MAK 5 half an hour after MAK 4 twice a day) I was on a permanent "high". I was soooo happy and my brain was like someone turned on a really bright light inside. It was such an excellent experience!
On the other hand, I found that it did not help much at a physical level and it was very expensive so I discontinued it. The mental benefits continued for months afterwards.
Since I was looking to improve my health (I felt tired all the time) I tried Chyavan Prash from Dabur. It was o.k. Later I tried Bheem Chyavan Prash by Yogiraj Jayant in Toronto, Canada. That was a lot better! Yogiraj-ji prepares it privately in his Ashram in Kanv, India. Kanv is deep in the Himalaya mountains. Yogiraj-ji says it is more effective because he (his disciples) pick the herbs in the wild and prepare the Chyavan Prash right away, while the herbs are still fresh.
I have used both MAK and CP from time to time for their respective benefits with good results. I find that the "high" I get from MAK happens within a week for me so I rarely take it for more than two or three weeks at a time.