I have a BX 23, would not want to be without it. For cutting grass it is great. For the retaining wall project it will be a back saver with the front loader, just plan on a lot of trips to the dirt pile............but hey more seat time that way. My drive is also paved and uphill from the road, snow is no match with the tractor tires on and 4wd. Also the neighbors around me love it, cause I do their drives too...........more seat time. As for the hoe, YES. 2 stumps becomes, digging for planting new trees, which becomes an ornamental pond, which becomes digging a trench line, which becomes removing a sidewalk, which becomes............you get the idea, you will never run out of things to do with it NOW that you dont have to rent one each time.
You might also consider resale value, Kubota is in the top on this area. I cant speak for the other brands, and all have good and not so good things about them, but this is my second bota, and if when we get our ten acres or more to build our retirement place on, it wont be my last.