The major benefit of LaTeX is its expandibility. Indeed, it's of limited use if you can't get in there and add new packages to get it to behave in just the particular way you want or need. I think this would be really hard to do in something like Techwriter. Although I can see having Techwriter export its equation system to LaTeX files would be very useful (as basically a GUI for LaTeX equations), surely if you need to use LaTeX for academic writing you'd be better just learning how to use LaTeX? Ok, you might say it would still be of value for knocking up simpler LaTeX files (no fancy packages, just tables, sections, figures etc) but just learning to write the LaTeX code for that would only take a very enjoyable Sunday afternoon. Plus, it's available of RISC OS (don't know how up-to-date mind).
On a related note i'm not sure how common it is for academic publishers to request LaTeX files from researchers these days. I've certainly never experienced it in the biological sciences, speaking as someone in a well-respected research university. They tend to want a Word document or a text file for the main body of text, along with all the figures in a TIFF file of suitable resolution with associated legends as Word docs. Then they sculpt the final output from those using I presume LaTeX or perhaps some other typesetting system).