Rachel,
Here's my experience with Pages. I bought it the day it was released (last January), installed it, fired it up, created a manuscript template in about 15 minutes (without reading the manual), and started writing my manuscript.
What I'm trying to say is that I've found Pages to be perfect for my needs -- so far.
What I'd do, if I were you, is to spend a few minutes building a manuscript template (or download Best-Selling Book at
http://www.iworkcommunity.com). Next, copy some text into it from one of your manuscripts, then format it using your new styles. Finally, export it into Word format, then open it in Word to see how it looks.
Pages has no annotation feature, so when it comes time to get feedback from an editor, have him/her write the notes in a different color.
There have been dozens of threads in this forum about how well Pages exports to Word. The concensus is that it exports text very faithfully, but may have some trouble with graphics. Since my manuscript is 100% text, that's never been an issue with me.
Good luck. Happy writing.