There is obviously some issue on what size blade the tractor can handle so let me weigh in one last time by saying the blade size a machine can use is really dependant upon how you are going to use it.
For a modest weight 24hp machine, the blade sizes most commonly used are probably 60" & 72". If you are using the blade to move lose dirt, or light snow, then 72" will easily be handled. If you are digging into the ground, such that you are not simply "grading" but in fact are using the length of the cutting edge to engage and break up ground, then 60" is better suited. The greater the resistance on the blade the more trouble the tractor will have.
I found that under heavy slush conditions, driving in reverse, 60" of blade, angled to one side, was about all the tractor could handle, but under lighter snow conditions (even if the snow was deeper) the tractor could move the mass of the snow with no problem at all using the 60" blade. The tractor could easily us a 72" blade in those conditions.
Under heavy slush conditions, blade facing forward & angled to one side, I could not PULL the heavy slushy snow in a straight line because the tractor would be push in the direction opposite to the way the blade was angled (I was NOT using tire chains, this was done on a paved driveway).
So I think we each need to look at our needs. Will freshly dumped stone or dirt be moved? If so, a larger blade can be used. Will digging and gouging of hard packed soil be attempted? If so, a smaller blade would be more effective.
As for snow, after only 1 season of using a blade, I gave up plowing and bought a new 60" blower (I had previously used a 48" blower on a different tractor for 8 years) But if you get modest snows and typically lighter snows a blade will work great. We just get heavy-icy-slush where I live! /forums/images/graemlins/frown.gif