hmmmm I've actually found:
CSS Layouts take a little longer to load:
because it has to load a single HUGE stylesheet, a javascript for workarounds and monitor resolution monitoring....because it's not truly and completely cross browser compatible
I'll give you that CSS is compatible with all browsers. However, not all CSS is compatible with all browsers, and you end up having to pack the CSS stylesheet with more css code to make it work, or include a large js javascript include to provide conditional workarounds.
Additionally, when resizing a css layout, you tend to get overlap of divs, etc. things don't line up the way they're supposed to.
Additionally you don't "NEED" css to be search engine friendly. You need proper use of content, code, and meta data, and link backs don't hurt either.
In my day job we used css to merely style the page. the rest is HTML, and when the new site launched on Oct 15th, we increased our readership from 5,550 per month, to 434,000/mo. Not too shabby for a non CSS layout eh?