Good question.
Steel is harder, but less forgiving. Feels closer to honyaki to me than typical monosteel, certainly more so than Ashi. I'd say you have to be a touch more precise with the Goku over the Ashi, which is forgiving. Holds an edge longer as a result though. It's got more taper than the Ashi, and as such, a little heavier feel to it, not by much. More mid weight, less laser except at the tip where it whips through onions and such. Grind is superb, same as Ashi, both have A+ grinds. Finish is more "working finish" while the Ashi is belt finish. Taller heel on Goku.