Hmm, not sure exactly what you mean by privately owned farm.
For instance, where I'm at now I would consider a relatively small, privately owned stable. There are about 12 horses on the property, 4 of which belong to the BO. But only two other boarders come out to ride on a regular basis (at least that I've run into). There are pro's and con's to this place just like any other. I like that the barn is usually quiet and I often have the arena to myself so there's nothing to distract me or my horse. On the flip side, I also don't have anyone to ride with when I do want company. We don't have a trainer on at the barn. Although we're welcome to bring one in for lessons etc., there's no one there on a daily basis to ask questions and bounce ideas off of.
As far as worrying about people using your tack, I wouldn't. Even at the bigger barns I've been at, it's a pretty strict don't use without the owner's permission policy. At the bigger barns too they usually have tack that gets used in lessons that people will go to to borrow from first.
It really all depends on what your goals are. For now, I'm just goofing off and working out the kinks on my green horse. For that purpose, where I'm at works just fine for me and at half the price it would cost me to board at one of the larger stables in town. If I wanted to get more serious about showing, I would probably move somewhere where I had more convenient access to a trainer. I don't know if that helps at all, but good luck finding a place that suits you.