I just got back from this year's Business of Software Conference (Europe edition). It was a good experience, and I recommend it to anyone considering it in the future. (The USA version is in Boston in September.)
It is definitely expensive compared to, say, MicroConf. So what did I like about it? The speakers? Well, yes, they were good, but I can watch past conference talks on the Business of Software website, so the value of the speakers wasn't enough to justify the cost. The organisation? It was meticulously run, but that doesn't make my business better. The real value is that the speakers and many of the attendees run successful software companies, and they all gave generously of their time over meals and drinks.
People running companies with 25, 100, and even 200 employees politely asked about my business, then offered insights into what I could do better. It helped me to hone my positioning and marketing strategy.