I'd like to try out some short trips first, say 5 days or so. Then maybe 10 days if the first trip works out. Is a 45L to 50L pack big enough for up to 10 days?

What brands are best?

I was looking at this pack -- is it any good?

http://www.eaglecreek.com/bags_luggage/backpacks/Truist-45L-10059/