If you are going to be mowing 6 acres, you need a 61" mower. I personally mow 4 acres of centipede with a Ferris 3200z with 61" deck. With a 37 HP Vanguard EFI engine it takes me between 3 and 4 hours. That's without any edging or weed eating. I had a Scag Wildcat with 61" cut, but after 14 years of bouncing I decided I needed to do something better for my back. The Ferris is hands down the smoothest riding machine I've found. I've tried Hustlers as well. No comparison. You're biggest problem is your budget. $6k is not enough for a machine that can handle that much grass on a weekly basis. Most all these brands have 0% financing all the time. Also, I would consider Hustler. They have one of the largest product lines with a wide price range. My uncle recently purchased an X-One 60" cut with 29 HP Kohler EFI for less than $9k. You could step down to the Fastrack HD or whatever for a little less. Find you a good dealer first and go from there. My dealer sells Scag, Hustler, Ferris, Snapper Pro.