Do you have any other uses for your tractor, besides mowing the 15 acre field a couple times a year, and finish mowing the 4 acres? Are you planning on doing anything with the remaining 56 acres of land you have?
Are you retired with a lot of time on your hands?
Are you the type of person who typically tries to use the smallest tool available, that is just enough to get the job done? I'm asking because some people have a lot of land, with a lot of work to do, that is technically possible with a very small tractor, it just takes a really long time. But, if your that type of person who doesn't mind, then a subcompact may be just fine. :confused3: