What are the advantages to intarsia over duplicate stitch? Is it just a matter of preference or are there times when it is definitely preferable to use the intarsia method? I'm knitting a Harry Potter sweater: would it matter for this pattern which I chose?
Duplicate Stitch Vs Intarsia
For that sweater, I might prefer duplicate stitch. The letter's thin enough on all lines that you wouldn't be messing with the drape of the resulting fabric very much. Also, you'd have to either have multiple bobbins going, or do something to carry the floats across the back of the H, so intarsia would be a bit of a pain. There are times when intarsia is definitely better, but I don't think this is one of them.
I use intarsia when I'm creating large blocks of color. So if I wanted to put a heart on the chest of a sweater (like this: http://www.ravelry.com/patterns/library/little-girl-big-heart-pullover), duplicate stitch would be really time-consuming, and it would make that part of the sweater weirdly bulky and stiff.