Nice review, mrogers. The only point I'd make is I don't think the 655 is replacing the 645, it actually seems to be a less expensive version - slightly bigger, without the nice metal carrying case and with less charging options (and a less expensive suggested retail price.) I think the 645 will continue to be available.

I bought an early 645, and had the early issues with the lack of a secure fit in the charging cradle. Eventually the clip broke, and I called Plantronics - they immediately sent me a new charge cradle at no charge and the new one is a better fit and more secure. As for the ear piece dropping down, I've heard that complaint a couple times, but have never had that problem with mine - it stays exactly where I position it and feels very solid. I love the 645.