It would be favourable, but perhaps not workable.
I've always viewed the current system as rather unfair, and potentially damaging in some cases - at least if employers had the same views as those on TSR. If, like some on this forum say, an Oxbridge degree is worth so much more than even a top RG uni degree, how can we expect these students to have faith in their education? Why go through the bother of working so hard, even for a First, if the guy at Oxford with the exact same degree and grade as you is going to be viewed as inherently better?
Though, luckily, this kind of attitude doesn't at all seem to have permeated universities themselves at this stage. For admission to essentially any Masters or PhD course, even Oxbridge themselves would not discriminate based on the quality of the undergrad institution. I find that to be a better way of looking at things, in some regards. Anyone who comes out of university with a First has significantly achieved, usually regardless of wherever they achieved it from.
I think a more important question, in fact, is how should we judge those who go to the top universities and underachieve? I would like to think that anyone in their right mind would think a First from somewhere like Manchester - or even mid-tier unis like Reading or Royal Holloway - is superior to a Third from Oxbridge. Unfortunately, not everyone on TSR at least seems to agree.
Perhaps if groups of universities could come to agreements over standardisation it would be beneficial. I think it would be very, very good, for instance, if the Russell Group agreed to standardise their grading systems. The quality of universities within the RG is close enough that such a system would function well, I believe.