Ragga says:
I’m kind of obsessed with knitting from the top. Due to some profound knitting psychology it’s a totally different experience than to knit them bottom up, not to mention knitting them in pieces that are sewn together… The reasons for my love of this method are for example that you can try on the sweater at all stages, it looks like something right from the start, and you can decide the length of the body and the sleeves as you go. First you´ll have a nice yarn necklace, then a cowl, then a poncho, a vest etc. You can virtually choose to stop at any time and still have something that is actually wearable. So I’ve started to knit my Lopi sweaters top down as well. The sweater Loki is knit from the top and is a great piece to start with if you want to get a hang of the method.

In fact you can knit most of existing Lopapeysa patterns from the top. It just requires a little thinking ahead. You cast on the stitches for the neck, knit the yoke, using increases instead of decreases, put your sleeve stitches (minus the underarm stitches) on pieces of scrap yarn, continue with the body, adding the right number of underarm stitches on either side, finish the body, pick up stitches for one of the sleeves and in your first round pick up the right number of underarm stitches from the “new” stitches on the sides of the body, finish the sleeve and knit the other one the same way. No grafting at the end and you can put the sweater on right away!

Two great books that I can warmly recommend are Knitting from the top by Barbara G. Walker and Modern top down knits by her disciple Kristina McGowan.