Please fix this.
It's a deal breaker for me as I'll stop using radgrid if my users can't change pages using the page field box. It's going to be annoying constantly having users tell me it's broken and while I could hide it that is not acceptable as some grids have hundreds of pages.
It's not a feature request.. this is a bug.
My solution would be to just make the go button a post back so you can grab the contents of the page field box and redirect in code behind. The page field itself doesn't need to be SEO enabled as search engines will spider through the numbered pages.