One Strand or Two?

I’m making this bag for my sister.
http://www.knitpicks.com/Projects/Projects_Display_Yarn.aspx?itemid=50402220&yarnid=5420103

(Sorry, I don’t know how to make the link be a word… make it so that if you clicked on “bag” in that sentence above, it would be a link to the bag. Could someone PM me on how to do that?)

Anyway… the pattern calls for using two strands of yarn on size thirteen needles. She wants me to make the extra large size. Before I have her order the yarn, I was wondering if we could get by with one strand on a smaller needle? How much smaller will that make the bag?

I guess I don’t know why it needs two strands when it’s felted anyway… is it just so it’s thicker after felting, more sturdy? Does it make that much difference?

I am currently working on this bag.
http://www.knitty.com/ISSUEwinter03/PATTfrenchmarket.html

It calls for one strand on size 7 and the picture on the pattern still looks pretty thick to me. I don’t see that much difference (in the pictures anyway) between the two bags.

So why the two strands in the first bag?


Another question about the first pattern.

(May need to open the PDF for this question, if you guys don’t mind helping me out here.)

It calls for a set of five double pointed needles. Where are they supposed to be used? In the very beggining, the pattern starts off with the base, then the edges are picked up and it’s in the round after that. Couldn’t I use regular needles for the base and then pick up onto the circ? (Especially if she wants the XL size.) Or, are the dpn supposed to be for the in the round on the smaller bag?

It does need I-cord straps, but that doesn’t need five needles. I’m just wondering why it specifically called for a set of five.

Thanks so much!!

The yarn called for in the French Market Bag is an Aran weight–heavier than a worsted. The Knitpicks bag calls for Wool of the Andes–a worsted that’s not especially thick. Since it comes in larger sizes, they must want to make it sturdy.