In a couple of projects recently, I have had a chance to see the value of viewing sites over a computer that does not access the web via the company servers. In one project problems with the company's proxy server made a site under development seem very slow. In another case, we set up an email address for customers to leave feedback. This actually comes to me (at least for now). Test emails originating from the developer reached me OK, but when I tested the email account myself, it didn't work. It turned out that successful delivery of the email relied on the mailing computer knowing an alias for my proper email address. So no problems from within the company, doesn't work for the rest of the world.
So it is well worth the project team experiencing the site from outside the company infrastructure - visiting it from home would be fine.