retain the main page, open links in separate tabs
It is time-consuming to have to wait for a page reload when returning to one's home page. It is also easier to make comparisons if an additional tab can be opened rather than closing the home page and replacing it with something different. The whole concept of tabs is to be able to keep several pages (URLs) downloaded at once. If you have to return to the previous page, you might as well go back to, say, Windows 98.