Looking for pratical quantitative comparison metrics for scaled, delayed and warped Signals
I'm answering the question the way I understood it - How can one find a similarity measure which isn't sensitive to scaling and shifting.

An approach could be borrowed from the Computer Vision world by comparing Shift and Scale Invariant features between the two signals.  

I'm not sure it will work for measuring the quality of recovering signals but it certainly will tell two signals are similar given the hierarchy between their features is similar and the features themselves are similar.