Yes, the R level model has been discontinued in the 5 family tractors. The "M" trim level has been expanded with greater offerings. Our dealership still has a few on order that should be here later this year. Inquiring with your local dealer may net you some results if they don't have the...
The 100 series Deere units will be the same at the box store as at the dealership. I work for a 5 store dealer in Pa and we hear that the large ag dealers don't put much effort into the riding lawn equipment category; most sell it simply because they have to. Good luck with the new S140!
Any sub compact 25hp tractor should perform well for you. Going to a Kubota B01 series or a 2025R Deere will provide better ground clearance and you'll see slightly better being up higher. I would pick the brand that provides the best dealer support in terms of parts and service abilities. Have...