I recently purchased a used Landpride FDR2572 for $1200. You can see pictures of it in my gallery. It was in good shape and the same unit would have cost me at least $2300 new in this area with pneumatic tires. It came with a spare tire and a spare blade. The only option it did not come with was the anti-scalp roller but I recently ordered this and I will be adding it on.
I usually prefer to buy new and I was about to buy a First Choice unit since they seemed like a good value for the money. However, I had always wanted a heavy duty Landpride FDR25 series but I wasn't about to pay over $2000 for a mower. I had to take the chance with used when this came up.
The gentleman I purchased it from was using it to "roughcut" his fields a couple of times a year. There probably was not too much heavy brush in the fields but I'm sure it was pretty thick grass. He said he had over 300 acres and was using it on a good portion of this, which I find hard to believe. Ultimately, he only used this for a couple of seasons then he traded up for an 8' unit. Considering this "abuse", it was in pretty good shape. It was always stored indoors. I simply sharpened the blades and greased all the fittings. It did have one bent blade so I replaced it with the spare. The metal dividers below the deck were also bent but were easily bent back into place. The gearbox oil still looked like new in it. In terms of rust, I have seen new ones on dealer lots that looked worse than this one. This unit seems to stand up well to the abuse.
Since he had already put it to the test, I decided to do the same. I mowed about 4 acres of wild field with it to see how it would do. The field was mostly thick grass & weeds. There was little to no heavy brush. The grass was easily taller than the operator platform in most areas and up to 4' in others. I kept the FEL on and simply lowered my bucket near the ground to push over the grass and probe for large mounds and rocks. I also kept the mower deck fairly high off the ground on the first pass and went slow. It mowed it without a problem and my 3320 rarely even bogged down. However, I did notice my ground speed slowed down a few times, presumably due to the load match feature.
With all of that said, the cut was not the greatest but it is coming around quite nicely after an additional pass. One or two more passes and you will have never known it was a field.
Assuming you have no major brush, I would start with a heavy duty RFM. Your machine can certainly handle it. If you are not happy with the results, you can always buy an inexpensive new or used Rotary Cutter later. The ideal thing would be to have both but it will cost you more and it takes up more room if you plan to store it indoors.
I can tell you one thing, I would certainly recommend the LandPride FDR2572 after seeing the way this thing has held up.
Whatever you get, make sure it is iMatch compatible if you have an iMatch.