This battery backed gyro is interesting, with a 1hr battery backup.
It is about $5000…
There are two questions however:
1 – With King autopilots, you still need to do something about the pitch/roll reference, which has to be one of
2 – does this new gyro need to be in the pilot’s primary field of view?
The EFD1000 has a 30 minute battery backup.
I am thinking of a single alternator single battery US-reg aircraft.
I contemplate getting a Dynon D1 as a stand by for the no gyro Super Cub.
Hopefully a good value TSO EFIS will come along soon. The non TSO variety seem to come in at around $1-3k, the TSO variety in five figures.
http://www.avweb.com/news/features/EFIS-Backups-Worth-the-Expense220989-1.html
Rather than spending 5k on one Gyro, isn’t one better off spending say $12,000k on a dual Aspen setup? I am very impressed with the Aspen and with a dual setup you don’t need the vacuum pump any more and you have full redundancy.
AFAIK, a dual Aspen installation (a PFD and MFD which at the press of a button could become the PFD) is not certifiable at present as both the primary and the back-up as they are essentially the same system (software and hardware) albeit in different boxes.
I do have a dual Aspen set-up in my plane and still required an independent AI, in my case the Mid-Continent Lifesaver, in order to get the plane IFR-certified. I can only speculate that this requirement is in place to avoid having no back-up at all should both units go dark at the same time due to e.g. a software problem.
In the US, Aspen has certified the so called “Evolution Backup Display” which, if I read this correctly, is nothing else but a standard Aspen PFD. It is, quote “Built to compliment existing non-Aspen glass cockpit solutions” which I translate to “not allowed as a back-up for existing Aspen installations”.
essentially the same system (software and hardware)
That is curious, since loads of big jets have the same kit LH and RH, but it’s OK because they have 2 engines, 2 generators, 2 buses, etc.
They also have 2 Ipads for Jepp terminal charts 
That is IMHO not clever since it is completely possible for a malformed plate to crash the rendering code.
AIUI the main issue with Aspen (preventing them from removing one’s vacuum system totally, on a single alternator aircraft) is that their battery backup is not long enough for certification.
