Whether embarrassing and privacy-invasive or not, it seems clear that full-body scanners will soon be a component of more and more airport security checks.
The degree to which they slow down the security process will depend on how they are implemented - as a primary security mechanism that all travellers will be subjected to, or as a secondary mechanism reserved for those deemed to present higher risk.
The primary model is shown below.
All travellers go through the scanner, and all are consequently delayed and PO'ed.
Conversely, the secondary security model PO's off only some travellers (this decision typically made by some questionably trained individual with a failed dream of making the RCMP or equivalent force).
A bonus of the secondary model is that those travellers not picked for the scan will be left feeling relieved, smug & schadenfreudic at the misfortune of those who are. I see a line of t-shirts exploiting this emotion, e.g. 'I came through security and all I got was a lousy pat down', etc
Given that I am a white male who gives off a strong computer geek biz-traveller vibe, and so am consequently unlikely to trigger whatever criteria will demand a secondary-scan, my preference is self-evident. (although I wouldn't mind viewing my own scan - it's so difficult to adequately track my glute progress in our floor length mirror).