Thanks for the info, I've been thinking about upgrading my card as well, and the 50k bonus points is a great incentive.
Your point about the "membership year" made me think about something - the upgraded Surpass card says that you'll be given complimentary gold status for your first year. Is this a full calendar year after you upgrade, or just the duration of your first "membership year". So for example, I got the standard Hilton card in March 2011, and am thinking about upgrading in October 2011. Is the complimentary gold good until March 2012 or October 2012?