Nutanix, Twilio are two recent ones (IPO'd in 2016). They both were great performers last year.
I don't have the time to dig up all the data and do a comparison of the correlation between returns on companies that used the confidentiality exception vs. companies that didn't, but it would certainly be an interesting analysis.
Are you sure Twilio or Nutanix didn't file confidentially before its S-1 was flipped public? I'm actually not sure if there's a way to tell, other than a leak.
I don't have the time to dig up all the data and do a comparison of the correlation between returns on companies that used the confidentiality exception vs. companies that didn't, but it would certainly be an interesting analysis.