I can definitely see myself getting annoyed sooner or later, if SIAI donors keep posting low-quality comments or posts, and then expecting special treatment for being a donor.

Me too. The reason I upvoted this post was because I hoped it would stimulate higher quality discussion (whether complimentary, critical, or both) of SIAI in the future. I've been hoping to see such a discussion on LW for a while to help me think through some things.