I'm happy that the two are separate in Safari. The combined address / search bar is one of the things that I really don't like about Chrome, and part of why I don't use it. Searching and typing in an address are distinctly different tasks.
The main problem for me is that I often see my typos about a fraction of a second after I hit Return. I know it's wrong and I just want to go fix it. But when something initiates a search, it completely changes the URL (no longer a simple fix) and the resulting page isn't even close to what I wanted. It all just slows me down.
Until that point I was forcing my browser to filter out most of the ISP's page, because it was naturally filled with unnecessary images and ads and crap and was just slow.