Hello, I am new here and in need of some advice. I have looked up specs and features and done all the homework I think I can do on my own, and I really need some help from you guys that have real world experience. I live on 6 acres, of which i currently mow about 5. There are some gentle slopes and one drainage ditch to mow around, but other than that, it is pretty much flat with a fair amount of obstacles. My current mower is an old, tired F935 with a 72" deck, and I am looking to replace it before it finally dies. For reference it takes me about 2:30 to 2:45 to mow everything right now, and probably 75% of the yard is smooth enough that as long as the ground is not hard as a rock I can mow full speed. Also, I pass a Kubota dealer on my way home from work, and I have gotten to know the people on the JD/Gravely/Stihl dealer pretty well since I have bought my trimmer, chain saw, and way too many parts for the F935 there. So after lots of searching and considering the dealer location/relationship side of things my initial thought was a used <600 hr JD997 or Kubota ZD331. I am a big diesel fan and I figure either of these two mowers could mulch with a 72" deck and last longer than me. I was ready to drive 100 miles to take a look at a ZD331 with <100 hrs on it when I decided to do some more searching for used mowers. This led to even more uncertainty. I started looking at JD 700/800/900 series mowers. It seems I can get lightly used ones for about 1/3 less than the ZD331 that I was looking at. The only things that concern me are I would probably have to go with a 60" deck, and I am afraid of what fuel consumption would be. So my latest thought has been maybe a new JD 400/600 series. I realize these won't last as long as the commercial grade, but if I can get 10 to 15 years out of one, surely my next mower will be even better, and I can buy two for the cost of a 997 or ZD331. But again i am worried about fuel consumption and power to mulch if I can't get to the lawn right away. Also, I think these mowers only have a 3 or 3.5 gallon tank. I do not want to have to stop part way though to fill up, or even have to fill up before I mow each time. Currently i have two 6 gallon tanks and I put about 10 gallons in at the beginning of the season and then add 5 gallons every 2 or 3 times I mow. So, what do you guys suggest? Go ahead and spend the money now for the top of the line diesel, get the used commercial grade, or a new consumer grade? Also, if any of you have experience with any of these mowers, what are your real world average fuel consumption rates. I am guesstimating my F935 is about 1.25 GPH. I am thinking if the diesels will be .5gph less than gas, then over 1,000 hrs (approx 10 years) I will save 500 gallons, which would almost make up the price difference.