Thats good it will reduce uneeded viewstate in the page and reduce the payload size, but you still should not use postback for no reason, ie use a link with an image instead of an imagebutton with a postback url.
postback is for submitting forms. Consider what happens when a user clicks your button and it posts to your home page, now it is in a posted state and what happens if the user clicks the browser refresh button? It will prompt the iuser "do you want to resubmit the form" instead of the expected behavior of just refresh the page.
The typical pattern used when processing forms is to redirect out of postback after processing the form so that this browser refresh problem does not happen and forms don't get submitted twice accidently.
postback does a post request and regular links do a get request, normal navigation should be done by get requests.