This depends on what you mean by "Opening" all the chakras! When I was learning Reiki we learned that if we wanted to help make it easier for someone dying and suffering to leave we open all their chakras.

Why would you want to "open" them unless if of course they are closed down which that isn't too healthy either. We can master size them, that does no harm.

There is even a story of Heiashi doing that on himself because he did not want to go to war. Not because of fear but he couldn't bring himself to kill anyone other than himself.

Chakras are our life centers, please read up on them a lot before fooling around with them.

Think of it this way, your heart beats normally everyday and one day you decide to find out what effects fooling around with your heart might have on you.