Mike Haubrich has an analysis that you should have a look at.
While I prefer a single-payer plan, I will also support a public option. Yes, this will drive some private insurers out of business. Considering the piss-poor way that they have been enacting the so-called “invisible hand” I don’t feel too sorry for them. The reliance on private industry has led to a huge drag on our economy. If a raise in taxes leads to a reduction in overall costs to employers and employees, and if the covered 250 million benefit financially through reduced debt and co-pay shares for health care, and if employers benefit because their employees get early treatment, and if enterpreuners benefit by being able to make it through tough stretches by not having to pay incredibly high individual plan premiums; then it makes economic sense.