"I may buy Twitter on the open depending on where it is. I wouldn't pay more than a $20 billion valuation because I think that discounts 2015 results pretty fully," another small hedge fund manager said.
"Twitter is well positioned with something like 65 percent to 70 percent of revenue coming from mobile already—and their product is tailored for mobile usage even if that was the original vision behind the 140-character constraint," the manager said. "For that reason alone Wall Street will love it—they want mobile Internet."
Other hedge funds aren't convinced.
"I am not looking at the Twitter IPO, since there seems to be way too much hype and media attention," Svetlana Lee, the portfolio manager at $66 million equity-focused hedge fund firm Varna Capital. "I tend to prefer under-the-radar-screen, misunderstood or unloved opportunities."
Another is Rob Romero, the portfolio manager for $120 million Connective Capital Management.
"We are not planning to invest. At the current valuation, the revenue model is not yet established enough, and their reach and frequency from an advertiser perspective is not as uniform as Facebook, particularly in the U.S. where monetization is much more established," Romero said. "Twitter users are typically enthusiasts looking for short nuggets of news. Facebook engagement is deeper and broader."
Many are basing their Twitter case—either way—on previous social network IPOs.
Graves, who is up an estimated 52 percent net of fees this year through October in Boardman Bay's flagship fund, said he prefers this IPO to Facebook's.
"Twitter is most likely an initially better investment opportunity than Facebook—the deal is cleaner, there is less retail investor exposure, management has been more prudent in their pricing and sizing and, importantly, the exchanges should be prepared this time around," he said.
Added another bearish manager: "Another way of saying this is it could be worth as much asLinkedIn? The big difference here is that Twitter's margins aren't great and are never projected to be amazing—Facebook clearly has a better business."
Lee of Varna said she prefers to wait on Twitter, as she did with Groupon: "I did invest in Groupon in May of 2013, but that was long after its IPO when the stock was pricing in a lot of pessimism and the market was ignoring the change in Groupon's business model," she said. "At the time, the stock was all but left for dead and the market was assuming it was still a coupon spam e-mail business, whereas the company was successfully transforming itself into a local transaction platform."
The largest technology-focused hedge funds—including Steve Mandel's $9.2 billion Lone Pine Capital, Philippe Laffont's $7 billion Coatue Capital and Chase Coleman's $6.2 billion Tiger Global Management—declined or didn't respond to requests for comment. Nor did employees of the banks leading the IPO, including Goldman Sachs, Morgan Stanley and JPMorgan Chase.
What other big money investors do remains to be seen. David Einhorn of $9.7 billion Greenlight Capital and Carl Icahn of $31 billion Icahn Enterprises didn't respond to a tweet to their handles requesting comment.
—By CNBC's Lawrence Delevingne. Follow him on Twitter @ldelevingne. CNBC's Seema Mody and Kayla Tausche contributed reporting.