I think that it would be a good idea to temporary suspend Davis-Bacon in the face of this country's economic environment. But I do so with reservations.
Here is an interesting paper that discusses the effects of prevailing wage laws and the quality of construction. The author believes that A, prevailing wages don't raise the costs of the project and B, paying prevailing wages ensures the quality of the work.
Quality Construction—Strong Communities
http://www.faircontracting.org/PDFs/prevailing_wage/PreConstIowa.pdf
With his claim about prevailing wages not effecting the cost of the project, he uses the reconstruction following Katrina. I think he should have been more expansive.
Regarding the quality of work, I have to agree with the authors theory. With construction projects you need high skill levels in order to have high quality work. I believe that 100%. Here's a short story that convinced me.
My stepson is a union construction worker, he worked for a company that specialized in concrete walls. The owner of the company wanted to see more profit and also wanted to be able to win more bids so he started another company doing the same exact thing, he put the company under his wife's name and it was non-union. Soon the union company laid off all of it's workers as the non-union company got all the projects. After a couple of months, the unionized workers were called back to either repair or do over the work done by the non-union company. Now the union company is back in full force and the non-union company was basically dissolved. It cost the owner of the two companies more money to go the route of cheaper labor because the work wasn't done with high skilled construction workers and had to be re-done or repaired. Plus the deadline of the projects wasn't met, thus costing the owner
Anyway read the link I provided, it was very insightful. (It's long citing research but it can be skim-read.)