Original Question..
And... just to come back to the original question, which worries me slightly as I re-read it....
As one of the blokes who used to be responsible for the engineering of the (civilian) systems that so many seem to be following outside the promulgated range... it is immaterial how far outside the correct range you can pick it up, it doesn't matter which aircraft type you are flying, if you use it then you are operating outside the certified parameters of the system. I know it goes on and I know it (mostly) works, but you ain't in a good position if something goes awry.
What can go wrong?
Well, the signal can bend all over the place, you could suffer from all manner of abberations and command reversals... I'm not suggesting it's going to fly you into a mountain but...
Just be careful now...
Now if you'll excuse me Mrs Doyle is coming in with some tea!!