Reasonable question Carey -- It was my opinion. I said it because the flail mowers are designed to be used with the roller on the ground, controlling the distance between the knives and the vegetation or soil or whatever. My use of the flail mower is on a wide variety of ground that is generally not smooth, usually has ruts and has mainly "pasturefield" characteristics rather than landscaped turf areas. If I ran the mower suspended from my 3pt hitch and not riding the ground then I am contributing/adding to the already nuisance level of 'bounce' at my seat which is unavoidable AND the mower will be constantly changing in ground clearance, thus producing a cut that varies in height and looks like crap. Anyway, that is my reasoning.
I too have a question: Prefaced by saying of course we each have individual circumstances and preferences that differ... but why do you want to cut 8" and higher ? If I bother to cut a section of land at all, spending time, fuel and wear and tear, then I want to cut it shorter than 8".