Skipro, just a word of experience. We build an approximately 1400 sf deck 13 years ago out of TimberTech, which was top of the line at the time. We went with hidden fasteners and the whole shmeer. And it has, for the most part, held up really well. But it's not maintenance free. We have to pressure wash it every year, at least after the first few years. They really have a tendency to get mold and mildew on them. Also, be careful dragging things across them (tables, outdoor firepits, etc.) They can scratch up, and you can't sand it out.
Having said that, they are much lower maintenance than wood, with no sanding/staining/coating needing to be done. A bit of caution and a bit of cleanup, and you're good to go.
Edit: Also, don't space your joists too far apart. It you get a lot of sun (looks you might not) they can slump a little. They still support the weight, but you end up with a little dip.
Good luck with the project. We're waterfront, so everything is mostly flat. I wouldn't look forward to your project, although I'd definitely love to see it when it's finished.