The MC-90 was designed to beat a ISD-II and could bring most of its guns to fire forward unlike the MC-80's which due their civilian designs could only fire their heavier guns braodside, MC-80 series they keep changing the stats for them, I prefered what they say about them in the Tie fighter game where they are much faster and nimbler than an ISD but more lightly armed with very strong shields, and in the hands of an expert can really hurt an ISD in in some cases beat them one on one.