CDSEO replaces both mods yes. Product Meta Tags are imported upon CDSEO installation so you don't lose current customizations. DSEFU urls can be 301 redirected (
https://www.websitecm.com/support/index.php?_m=knowledgebase&_a=viewarticle&kbarticl eid=67) to preserver current search engine rank.
CDSEO is W3C complaint for valid xhtml.