Using a reserved characters in a query string in hash fragment

I am trying to save the state of a client sided web application in the hash fragment part of the URL as shown below

http://ift.tt/1IW34pL 

I would prefer not to encode the hash fragment to try and keep the URL length as short as possible.

I have done some testing and everything seems to work just fine cross browser.

However, I have read that one of the characters I would like to use (backslash) is reserved for URL query params.

My question is are there are any consequences of not encoding the reserved characters?