I do have two minor quibbles:
1. You identify Mr. Yauch as a "songwriter" with no other explanation of who he is. If I wasn't bored and curious tonight and decided to Google the name, I would have had no idea you were inviting me to hang out with a member of The Beastie Boys. This is fairly critical information for a fundraising effort.
2. Sending out this type of invitation on May 7th for a May 20th event is kind of bad marketing as well. If you'd sent me this invitation back in December when I could have actually booked a reasonably priced flight I'd have been much more likely to attend.