We've had the last one you linked
(http://www.gyrohouse.com/catalog/items/item551.html ) in a club 182.
It's got about 850hrs on it so far with no problems at all. Although we
haven't needed to use it in a vacum failure yet it makes me feel
fantastic in the clouds to "see double".

Also I had an alternator failure when IMC once and the little red flag
that popped out on this AI was what made me first notice the failure
(this 182 has no low voltage light- just an ammeter).

The other nice thing about our installation is that the second AI is in
the old VOR 1 hole, which puts it just two holes away from the primary
AI. I think having it as plainly visible as possible is important if
it's backing up the vacum AI.