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.
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”.
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.
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
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.
