I agree with rScotty that your need for a backhoe depends on your land and what you intend to do with it. I would add that it also depends on your approach to working on that land, especially whether you have big plans to do a lot in a short time, or whether, like me, you want to do it in small bits as you get the time and energy. Certainly, there are times and circumstances where it makes more sense to rent.
In the year and a third that I've owned my JD 4600 with loader and backhoe, I've used the backhoe for:
Digging out rocks
Digging out stumps
Pulling out a downed tree from the far side of a ditch
Excavating alongside my house foundation to repair a crack
Excavating for and placing concrete piers for both my shed and my deck
Reshaping and improving a ditch
Putting in culverts
Fluffing up an old partially burned brush pile before burning again
Burying a rock deeper that was too big to pull out
Moving rocks to align with the Mrs' landscaping ideas
Pulling out shrubs that the Mrs wanted to get rid of
regrading rough ground
While it's true that some of these chores could have been done without the backhoe, most would have not been so easy without it.
Most of the above jobs also included the use of the loader. The following are some of the additional jobs I have done with the loader:
Snow removal on my 300 ft driveway and parking areas
Moving and spreading gravel
Moving firewood
Hauling waste wood, stumps and brush to my out-of-sight "rot piles"
Unloading things from the truck or the trailer
Delivering the grill to my new deck
Backdragging fill
Moving a shed
Moving pallets
I like to operate the backhoe. At this point, I would say that I have at least mid-level skills with it. I also like the fact that it's there whenever I want to use it. On my 19 wooded acres, I'll never run out of work for the tractor, including the backhoe.
I could have bought a new smaller tractor with loader for what I paid for my 2001 JD 4600 with loader and backhoe. I'm glad I bought a size or two larger than I started shopping for. I'm extra glad that I held out for a deal on a machine with a hoe.
Your mileage may vary, but for me, the hoe makes the tractor much more useful.