Realistically, it would only make you faster on the hills. And then not much. I used a calcualtor to find out how much faster I would be on a local climb if I went from my 25 pound bike to that 17.5 pound bike. I'd gain two tenths of a mile over the ten mile climb with 5% average grade. So my average would go from 6.8 to 7.0 mph and I'd save about two and a half minutes. If you're racing or planning on doing long hilly rides, it would be worth it.

Here's the calculator I used.

http://www.kreuzotter.de/english/espeed.htm

However if you just LIKE the bike - that's a good enough reason in my book.

V.