You had a lucky escape
The Iphone would have been useless because it is not self erecting. You have to be straight and level and press a button to tell it so. Then it works for, I guess, a minute or two, well enough. There are things one can do with cheap gyros which are well known (visit any "homebuilt aircraft" exhibition) but these Iphone apps are useless.
I don't know anybody who files serious IFR who has less than 3 gyros: a vacuum AI (or in very modern fits an electric one with a separate supply) and an electric AI, plus a TC. I have all 3 too. It is inconceivable that one would lose all 3 at the same time, quickly. What is possible however, in a high workload scenario, is that one might be focussed on the main AI and not notice its failure.