"You pays your money and you takes your chances." What I am saying is that I  see a couple of vacuum pump fatal accident cases a year. I also see a lot of GA instrument pilots for checkrides and refresher. IMHO if you you are going to fly IMC then you better think about having a backup horizon (not a turn and bank instrument). You also better have a backup vacuum pump or electric system. A B&C backup alternator for $400-700 is a great value. A RAPCO backup vacuum system will probably cost that much or more-- and all it can do is pump air (I think Brent Regan said it here first). Either way, a second AI and a second source of instrument power is important. Jeff