Most startup folks would say no; these speakers are unlikely to say anything new about the topic that I don't already know, and the attendees probably aren't decision-makers. If I had to pay I would agree, but since I don't it gave me an interesting opportunity to reflect.
What if the benefit from attending a corporate event is not to meet power brokers or learn new ideas, but to understand how the people who will be driving adoption of your product see the world?
In the startup world we lose track of the digital sophistication of the rest of the world . If you have a B2B startup, you are almost certainly selling to customers who are less digitally savvy than you. You will have to struggle to get anyone to care that your software is superior to the incumbents' because it can do XYZ thing that is so obviously important. Execs with high-level visibility might understand the company's pain points and how you solve them, but all lower-level employees see is the headache of having to learn a new tool when all they want is to do their jobs and get home to their kids.
Depending on how badly they need it, the executive who buys and champions your product might be able to drive adoption against their employees' will, but that's an uphill battle. More likely your would-be buyer will say, "We're just not ready for this" or "we can't push this through IT," or worst of all, sign a contract and lead you into a rabbit hole of work only to find out that they never completed their part of the work to get your deployment live. Very few startups can "pull a Salesforce" and sell lots of licenses to senior managers while rank and file employees hate or don't use the product.
How do you learn what corporate users - not executives - want? How do you understand the innovation maturity of an organization, its readiness to assimilate new technology? Traditional lean methods are great when your customer is a single autonomous actor, but they fall apart when your customer is a complex organization with competing internal interests. The most common method in enterprise is to spend 10 years in the industry getting to know its problems, then go do a startup to solve them. This is great but it's not something you can plan for. Another method is to read industry publications and swap intel with other B2B entrepreneurs.
Could going to summits with the middle managers of the corporate world on how to use technology be an opportunity to learn this? To get a sense of their fears and motivations when it comes to adopting new technologies? To stay grounded in your customers' reality? It's an interesting thought - conferences as "user research." I haven't completely convinced myself of it, or that it's better than the alternatives. What do you think?
 Josh Kopelman wrote a great post about this back in 2006 that is as relevant as ever.