To each there own but for me, the Guardian is definitely worth the extra money. Biggest obvious difference is bobtailed frame which will conceal better and I love the way it looks and how it feels in my hand. The other big thing for me is the Guardian's TG is undercut which provides with a better and higher grip, especially for people with big hands like me. The Guardian also has the "memory bump" grip safety as opposed to the flat style in the Vigil. Lastly the Guardian is a few oz's lighter.
All those differences, especially all put together, are major IMO and definitely justifies the added cost.