I recently made the mistake of writing a novel with each chapter as a separate document in LibreOffice. When I needed to combine them all into a single document, it wasn't pleasant. So that might be a consideration, depending on how many chapters your thesis has. As Imi mentioned, LaTeX definitely has better support for combining documents.
You might be interested in Lyx. It's a word processor that uses LaTeX as a backend. You can get almost all of the abilities of LaTeX, but the learning curve is a lot shallower since it has more of the standard word processor features. It's a big help in following shane's advice not to get caught up in the minutiae of LaTeX. I use it for linguistics, where it seems to be pretty widely known. (Linguists have some of the same typesetting challenges as the math people). It doesn't have change tracking, so you still have to contend with that (there's a patch to add it, but the patch doesn't seem to work that well). Also, if you do decide to use source control, Lyx can help you manage it, although it might take some coercion to set it up. Lyx uses its own file format by default, but you can export to LaTeX.
As shane also mentioned, there are tools to convert LaTeX into other formats. Pandoc can even convert LaTeX into Word or Open Office format. Both Lyx and Pandoc are available for Ubuntu.
So what I would probably do in your situation is write in Lyx or LaTeX, then use Pandoc to export that to docx or odt for your advisor. You can read your advisor's comments in Word, make changes to your original, and export again. It sounds convoluted, but I do think you'll gain a lot in flexibility and tool support over using LibreOffice.