I'm in the process of doing it right now. My case might be a little different as I'm good friends with the owner. My friend has been trying to sell/give away this mare for years because they don't click under saddle, but since she hasn't been riding her, no one wants to buy her. I currently have a horse, but she's blind, so I was looking for something I could jump. So I needed a horse, she needed someone to ride her horse, so a free lease just kind of happened. I was just going to ride her horse so she could get it sold, and well, it ended up she did get her sold--to me!
Anyway, long story short, her mare and I are just a great little team. She had never jumped before, I only have a few months jumping lessons, so we are green on green, but we just work. The mare trusts me, I trust her, and I've taken her on trails, shows, trailer out for lessons, etc, and I just love her to bits.
I think the lease to buy option is great if you have a quirky horse. This mare has a bunch of strange little quirks. I knew about all of them before I started riding her, and now they don't bother me. On the other hand, if I was going to go look at a horse and the owner told me about all these quirks, I more than likely would have passed. With the lease, I was able to figure out if they were deal breakers for me or not. Obviously they're not
We had a very nice horse that vetted horribly, but somehow managed to get to every show and win a ton. We finally leased her to a girl, with an option to buy at the end of a year, with her lease $$ applied if she bought her, and, yes, they waited til the very last day. They bought the horse, which has since won multiple championships at 3' and 3'6" and has never taken a lame step, although her x-rays say she shouldn't be able to get out of bed in the morning. That was 4 years ago.
I free leased a horse I was trying to sell. In the summer the horse had a minor injury and I pulled her from the barn she was at and brought her home. A couple months later, after the leasee had tried leasing another horse, she called me to lease back the same horse. I told her she had to buy her. I gave her a payment plan and some other stipulations, but the price was much lower than I was trying to get prevoiusly. She bought her and loves her. This wasn't a green horse but it was a green rider.
Daughter #2"s horse started out as a free lease. They totally clicked and when the owner said she really needed to sell him, I knew he'd be the right horse for her even though I wasn't planning on buying a horse then. The good part about having had the lease first was that I knew a bit of what I was getting into.
I knew the horse was well trained, knew his job, suited my kid, would take care of her, and teach her a lot. I also knew he was not an easy keeper, had crappy feet, was prone to ulcers, and would require some joint maintenance. I think I was able to weigh the pros and cons and made an offer that I was comfortable with.