Have a Vigil 9mm CCO and a Govt. model. Both are excellent guns for the money. Nicely appointed with all you need and nothing you don't. In the current market they are, IOHO, about as close as one can get to a semi-custom for considerably less money.
I have a Guardian 9mm, it is excellent and anyone who shoots it likes it. The different models just reflect a variety of features and those features speak to people on an individual level. Should the features be close enough to being the same, then either will bring you joy.
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.