Go down half a size from your true size. (ie I am a true size 9.5 so I buy my 576s in a size 9)
The 576 has a slightly bigger toe box area and the overall shoe runs wider.
Comfort Factor Ratings:
Cushioning (Softness): 5/10
Stability (Firmness): 7/10
Cushioning to Stability Ratio: 5:7
Midsole Shape (Foot support): 5/10
The 576 is pretty much just the MiUK version of the 574, therefore they feel similar on feet in terms of comfort. The 576 is a pretty comfortable retro runner. It won't blow your feet out of the water like some of the newer 990 models, but it is pretty comfortable for regular lifestyle/casual wear.Â