I would say that 90%. I don't know if Half-pixel scrolling is emulated, it may be interesting to check if scrolling is as smooth as an a500...
For AGA it may require even more resources because you would need a 1280 pixel wide screen to emulate quarter-pixel scrolling, I know that some games used it but I can't remember the names. My AGA amigas were bought too late and I was more interested in coding and using apps than trying out games.
EDIT: Oh yes! Worms used quarter-pixel scrolling :-) It may be a good idea to put an A1200 next to a pc with winuae with vsync enabled and a 1280x1024 screen (so real quarter-pixel scrolling can be emulated correctly) and check if it's as smooth.
