I am interested in builders' thoughts about having all electric gyros instead of the more standard system with vacuum driven heading and attitude indicators and an electric turn coordinator.  I've noticed that the Cirrus is dual electric, and the Columbia may be going that direction.  Ignoring the fact that electric gyros are more expensive, I am specifically interested in people's opinions about the following:

1. How much redundancy is required in an all electric system for it to be as safe as the "standard" vacuum/backup vacuum/electric system?  By "standard" system I mean a vacuum driven heading and attitude indicators, the precise flight backup vacuum system, and an electric turn coordinator.  Are vacuum systems so unreliable that even a system with one battery and one alternator is preferred?  If not, would a system with one battery and two alternators be preferred?  Two batteries and two alternators?

2. What are the failure modes in the different "all electric" systems that one needs to worry about most?

3. Beyond the Aeroelectric Connection (http://www.aeroelectric.com/), where can I get more information about this?

Thanks much.