Tom, the b6100dt, 4wd, is one heck of a tough tractor for it's size. If that is what you're looking at, I'd go for it. Especially if the 100 hours is correct. (sounds to low, but you never know) I've had my 6100 for 7 or 8 years now, and I've never regretted getting it. It's 3 cylinders, 14 hp, (11 pto hp) R1 tires loaded, 4 1/2 ft oversized after market FEL, 6 ft back blade, and used to run a 4 ft Flail mower. As long as you take little bites, you'll be amazed at what you can do with it. I dropped an 85 ft X 3o ft compacted gravel driveway 2 feet. And, never got the thing stuck so bad that I couldn't get it out using the FEL.
If someone gave me a new tractor, I'd still keep my 6100. Just something about playing in the dirt while your elbows drag in it.
Keep the greasy side down.
Mike