Have there been any corporate lawsuits, class action or otherwise, against issuing companies from Reg CF investors? What is the likelihood of this occurring (if ever)? What about from Reg A+, Reg D investors - would that be more or less likely?

I am aware of several lawsuits (including class actions) relating to the early Reg A offerings that listed on Nasdaq.

As for Reg CF, there is a case of fraud being handled in bankruptcy court.

Reg D: these cases are unfortunately quite common, both from investors and regulators.

It's early days yet for CF. Class actions aren't worth it for really small offerings.