One of my sites dissappeared from google for over a month. After racking my brain trying to figure it out I too learned of the problem people are attributing to the sitemaps so I deleted the sitemap and was back in 2 days fully indexed. Now there are so many variables as to why certain things happen with your site. There are good arguments to both sides of this fence, but with all the problems one can have with a site, I don’t want to leave anything to chance so I will not do google sitmaps again. There is too many things up in the air with this and there are too many webmasters who feel it is hurting them. In addition, it is my feeling that the search engines come around naturally by default, and I am not sold that submitting your pages via xml sitemap gets them indexed any faster. It is tough to come to any definitive conclusion regarding google, some people have no problems, others have a ton. All I know is what worked for me and after racking my brain for a month I deleted the sitemap and poof, 2 days later I was in action again.