A member of the NAM community on FB who is very passionate about reducing aliasing.
He goes to great lengths to test and discover new ways of getting this done.
The methods involve augmenting the training signal with additional signal/sweep patterns. These, however, may be risky on some equipment as well as extending training times.
Some challenged this because the training overhead & accuracy gains are somewhat bordering on the point of diminishing returns since most can't distinguish a standard NAM profile from one derived by means of these new anti-aliasing methods.
Apparently some people are very bothered by aliasing; personally I find that most NAM models turn out great with a solid reamp chain.