In the 800-speed films I've only used Kodak Portra 800, seen in the first example below in 6x4.5cm format, and Fuji NPZ 800. I've used quite a lot of the Portra and it's been very good, with my only criticism that it's not as good in mixed lighting as Fuji NPZ 800. The next example is the "Juice Bar Lady" shot with 35mm NPZ, and then a full-scale crop from the same 2000x3000 pixel scan. It does show grain, but the picture is pretty sharp.
Worth noting that I set my meter to 400 or 500 for these films, not 800. I give them that extra 2/3-1 stop exposure to open up the shadows and smooth the grain. (Processed normally.)
I use the 800 speed films almost entirely in 220 size, keeping some 35mm NPZ for special use. In either film size I prefer ISO 400 pro films as a standard for general purposes, and the ISO 160 when I know I’ll have plenty of light.
In what way was the Max 800 awful? I haven't used it... curious.