I'm cutting about 6 acres - some of which is open field with gentle rolls. The remainder is slightly sloped yard around a house. I really like the newer 72 with the 35hp engine and have tried to read reviews to compare the 72 to the 60. I really don't see much on the 66. If I understand correctly, they all come with 26" tires in the XS series. I've also read about the uneven striping on the 72. How about scalping on the larger decks? If you had to summarize, what are the pluses and minuses of the 60, 66, and 72 and which one would you buy? Thanks!