I have flown Vanguard once (and was delayed) and have driven to the airport to pick up friends flying Vanguard on numerous occasions. In my limited sample-set of flights, almost every one was delayed by at least 30 minutes - usually more. Not to say I wouldn't fly them if I absolutely had to choose between them and the 'Hound, but I do tend to avoid them - as well as most similar carriers.

In my experience, I've usually been able to find a comparable airfare on one of my more frequently-traveled airlines, so it's rarely an issue.