(15 acres, 10 acres hay and horse pasture, five acres yard, and woods)
It's hard to determine what you really need unless you say how you intend to use it. If you are going to mow 5 acres of yard or are you going to be in the hay business?
I have a 3510, never hurt for power, and it is pretty easy on diesel, unless bush hogging, it drinks a little more then. I also feel even the 3510, could be too heavy to mow with a finish mower. It would tear up the yard somewhat, depending how particuliar you are I guess.
I always was a bigger is better guy, even thought how nice it would be having a bigger tractor. Then I realized that it was'nt needed, in my particuliar case. I have been quite happy with the 3510.
Why are you replaceing the 1910 Ford? Have you outgrown it? The 3510 might be a little more tractor and the 4110 is definately more tractor. Depends on your needs....
TractorData.com - Ford-New Holland 1910 - Ford 1910
TractorData.com - Mahindra 3510 - 3510
TractorData.com - Mahindra 4110 -4110