Khiggins, you might consider starting a new post, if you are looking for a comparison between these two tractors. You might also want to indicate if you are looking at the 2WD or 4WD 5055. If you are going to do much loader work go with 4WD. I would also look at getting a tooth bar, if you are going to use it to clear load. At a quick glance at the 4005, I would not purchase it, because transmission is collarshift (have to stop to shift gear and range), 35 HP PTO and 5055 is 45HP PTO. Not sure why you are going to be bush hogging every 2 weeks, so I thought you might find this URL of interest.
TractorData.com - Mowing with tractors
TractorData.com - Mowing with tractors