In recent years, buttoned-down New York City has become an epicenter of open-collared consumer Web startups, with one hot brand after another drawing in users and venture capital in tandem. But the city that doesn’t sleep may have to work through the night reinventing itself if investors’ growing infatuation with all things enterprise goes unabated.

Most of today’s founders will fail. And when they do, they probably won’t leave with riches or celebrity. At least they’ll have a fairly solid resume.

Thanks to astute deal-making, a strong point of view, and a long and savvy relationship with social media, Fred Wilson of Union Square Ventures [USV] is widely recognized as one of the most influential venture capitalists in the country.

His influence is about to be tested.

Let’s face it: VCs speak their own language, and it’s sometimes more frat boy than Thoreau. We all know the VC who says to “trust the process” or who goes on “pity dates” with entrepreneurs. Others might joke about “putting lipstick on a pig” of an investment, or point to a newly acquired startup and say of its founder that he or she “pulled a Patzer” (i.e., left money on the table by selling too quickly).

I hate to say that Sigma managing director Greg Gretsch has inadvertently taken things to a new level with the title of his new blog post, “Don’t Let a Venture Capitalist De-flower Your Startup Without Making a Commitment.”

Still, the post has a thought-provoking premise: If an entrepreneur is going to be dazzled by a top-tier VC firm that wants to help seed his or her company, that funding had better come with a board commitment from the VC. Without one, the entrepreneur is facing a “double-edged sword.”

Greg Gretsch of Sigma Partners has reason to feel confident about his future as a venture capitalist. He backed the storage company EqualLogic, which sold to Dell in 2008 for a tidy $1.4 billion in cash. He led an investment in the Web services management company TalkingBlocks, which raised $9.5 million from VCs and sold to HP. (Details weren’t disclosed but Gretsch says it was a 2x for Sigma).

Gretsch has also seen some nice exits from angel investments made long ago. The audio player company Slim Devices, founded in 2000, was one of those deals. It raised $5 million and sold to Logitech for $23 million in 2006. Gretsch was also an early backer of Postini, which raised $26.45 beginning in 1999. It sold to Google for $625 million in 2007.

Even still, Gretsch says that as he enters his 10th year in the business, he’s worried about a tipping point. To wit, Gretsch doesn’t think that the longer you’re a VC, the more skilled you become in picking winners. Instead, he theorizes that if you’re a VC for more than 10 years, you’re likely to grow worse at your job over time.