I have them on my 2660 with 60"MMM. I noticed a substantial difference in the stability feeling around my property. I also liked the fact that they give me more room for the tire chains in the winter.
The only downfall I found is that the rear wheels of the MMM can not be turned sideways when removing the deck. I found that it is not that much of a problem though because the wheels will slide easily on smooth concrete where I remove the deck.