As a former Gartner Research Fellow and someone who talks on a regular basis to analysts from all the major analyst firms that put on events, I know that the vast, vast majority of analysts simply do not incorporate whether or not a vendor sponsors an event into the relationship. Another data point is that I use to be the director Corporate AR at one of the largest vendors and when I told analysts I would not see them at one of their conferences because my company was not sponsoring all I got was a shrug.

For one thing, analysts are not measured nor bonused on vendor sponsorships. That is even more the case during a recession when companies in all industries are cutting back on travel, marketing sponsorships, etc. While a sales rep might be frantic to close some deal, the analysts don’t care.

Your point about “Many vendors indicate privately that they are afraid…” is a quite common attitude. But that does not make it true. Same urban myth that surrounds buying annual subscription contracts

http://sagecircle.wordpress.com/2008/01/02/analyst-integrity-issues-the-urban-legend-that-wont-die/

While having an annual subscription provides useful tools, such as inquiry, the mere act of signing the check does not do a vendor any good. It is what the vendor does after they sign the check that is useful. A vendor that buys a million dollars of advisory seats but whose people never make inquiry calls will find itself out influenced by a vendor with a single $25k advisory seat but who leverages the access to analysts on a frequent basis.

BTW, Gartner is a $1.2 billion corporate, Forrester had $241m in 2008 revenues. Any particular sponsorship is an accounting rounding error and probably less than what the firms spend on paperclips.