ali1986
This issue is not about total instrument failure, this is about loss off the FMC. this will result in the loss of the map function and so the crew being forced to return to the glass reprisentation of "clockwork dials".
This requires a good mental picture of the aircrafts positon in space and the ability to switch quickly to navigation without the big map. What I have seen from graduates of the magenta line kindergarden is a state of panic when the FMC has a bit of a brainfart, the result is the FO going head down pressing buttons in an attempt to get the FMC back rather that containing the situation by reverting to conventional navigation and then trying to get the FMC back.
All this usualy happens on the SID or STAR when without quick action the aircraft can very soon stray off track. Add to this high ground and a non-radar enviroment and you have all the makings of a CFIT.
As for doing trainning on "basic" instrument flying during a jet type rating this is a non-starter, these courses assume that you have a good level of basic insrument flying and if you can't hack it you will be out on your ear!
Doing the IR on a glass aircaft will not equipe you with the basic tools of the trade and you will be a worse pilot for it.