Only have 34.5 hours on mine, and I love it. Granted it is my first tractor, I'm sure I would be more than content with anything, but I think it's sized right for my needs.
I have five acres, two of which I mow with a smaller mower, and the other three is field which I want to reclaim. My property backs onto my neighbours 400 acres and he's started to reclaim his fields as well. I bought the tractor for brush hogging the field, driveway maintenance (both summer and winter), leveling out the two mowed acres, landscaping and moving fill, and maintaining a trail out back as well. Anything bigger I would be concerned with tearing up the lawn with R4's, as I don't think the turf tires would cut it for the work I want to do out back, and anything smaller, I don't think would tackle the tasks out back. For ME, it's what I think is the perfect medium.
I will add though, that as already mentioned, the step and floorboard does move when getting on, but once on, I have not noticed any other movement. Nor have I hung off the fender to attest to it's durability.