Output both to 6mp files which is likely a more realistic output for print size
I did a capture on the A77 jpeg and raw
I have not done an in depth jpeg v raw comparison..yet.
Conclusions so far, the A77 is def giving more real exposure than the A57 at high ISO settings with identical ISO and exposures. This could indicate the A57's ISO values are overstated more than the A77's. The A77 does have a bit more chroma noise esp shadows, but not as much as I thought it would If I match the actual picture brightness (ie ignoring the exposure and getting the same result picture wise or near to it) from the cameras there are 2 ways of looking at it
The A57 will have less noise chroma and luminance because it's had more exposure, or the A77 underexposes even more will certainly show more noise than these shots do. However once I take into account the different real exposure that's happening, I think the differences are not much. At sensible output levels there isn't a lot to pick hairs with.
I would say though, if you shot at ISO 3200 on the A77 and used the default metering (multi segment) you're asking for more trouble than you are on the A57. Both cameras do tend to give less exposure than I think is appropriate (even though the A77 is letting more light in). I have to test the metering more to spot any differences here, this is why I used the same exposures for this test.
Though I would add face detection does influence the exposure so real world people shots in lower light might not require as much or any significant exposure adjustment. The metering can react to areas or light and dark I have to investigate this more. In real world I'd add a bit more exposure to the A57 at high ISO, I would suggest adding a bit more on top for the A77
Jpeg v raw will look into this more. The shots are 100%, this isn't a high detail scene but the jpegs struggle more with coloured areas esp reds (from what I've seen so far) this shows on the shot above, the red blotching effect. There is more luminance noise than I'd like, but will test this on a finer detail subject.
I did try adding more chroma NR on the jpeg file in LR5, it did improve it a bit (though not entirely removing the problem)
Will do some more tests shortly
So far I would say the reason the A77 is regarded as a noise monster is likely more to do with the conservative metering (pulling up underexposed ISO 3200 in post can be done..a bit, but you can't go mad) Even if you don't pull the images up in post in many cases you are not giving enough exposure and simply making things worse noise wise (the noise pattern tightens up with better exposure, easier to clean up) Blow for blow any differences are not significant taking into account normal output sizes, though there isn't a lot of point having 24 or even 16mp files at this high ISO level. I might do a higher ISO test, I consider 3200 to be usually as high as I sometimes need to go, though both cameras are capable of ISO 6400 with reasonable printable results, subject to more careful processing and you can't screw up the exposures at that sensitivity