I abandon many web sites who don't value my time. I don't mind giving you an email address to get a white paper, but more than three questions and I'm gone. Recently I went to the Tide website (don't ask why) and they asked if I could fill out a short survey. Sure, why not. After page 7 of 11 pages I went away. I'm not impressed with P & G's marketing prowess.
So if you want feedback from your customers, keep it essential and keep it short.