I knew a few guys on H-1B who switched. The only downside is that the clock is not restarted, but since the H-1B timer is 6 years and GC takes about 3 years, a worker who's not a complete idiot has plenty of time to shop around.

Hiring H-1B for cost reasons is not possible. It is not allowed to pay less than market price and the government audits it. My first H-1B job paid $75k in '97 dollars (e.g. north of $120k now) and it was more than typical market value. Full bennies, too.