Never had a green card - but going in and out of the USA on a european country passport with an H1-B was always a hassle.

Especially one return from a conference where the minimum-wage-moron on passport control didn't understand the concept of visas (to be fair he had a limited understanding of the concept of passports or even other countries) and allowed me in for 24 hours which I spent queuing at LA's delightful immigration office downtown.

Still, well done to him for protecting the USA from another foreign Caltech physics prof.