ahh you asked specifically about Malware blocking, got distracted by Synthetic getting automod timed out for an hour when he mentioned .3 blocking nsfw and thought you were asking about that lol.
I don't know how correct it is about malware. Overall, with nsfw/etc sites, the categories seem right most of the time. I've only dealt with it false blocking things, it does seem fairly fast about picking data up from those malware reporting websites, not sure which one it uses as sourrces. One guy got his site reported on one of those, and he was on Radar like ~2 days later complaining about it blocking his site
With ZT there is a number of other options you can pick as well, like blocking brand new sites, newly seen domains, etc.