I'm glad to read that PLoS is working on better TeX support. I strongly considered submitting a manuscript to PLoS ONE - until I read about the RTF/Word limitation. Having to go through some painful steps with regard to LaTeX to Word conversion for PLoS Comp. Biology, I don't feel like doing that again. Therefore I'll wait until PLoS is LaTeX ready.
As an aside, my own (anecdotal) evidence is that LaTeX (and Linux and OpenOffice) users tend to be strong supporters of Open Access - another reason why I think it would be very good for PLoS to improve their LaTeX support (to get it to a level found at for instance Physical Review journals). I hope it will happen soon!