I've been wanting to knit this free pattern forever, and last year around this time when I found out that I was having another boy, I put this in the "babybrudder" tagged section of my Ravelry queue. Then I started reading that the pattern ran small, and I realized that the specified gauge of 15 stitches over 4 inches in aran weight would result in a loose fabric that I wouldn't be happy with.
I finally cast on for this sweater at the beginning of October and decided to try my luck with chunky yarn. I cast on for the 0-3 month size in Dream in Color Groovy in Cloud Jungle (one of my all-time favorite colorways), using 10.5 needles and 10.75 needles for the sleeves in the round.
After several false starts (I blame the sleep deprivation -- we're going through a really rough patch right now), this was a quick knit, and a well-written pattern. The only downside to using heavier yarn is that this will function more as a coat than a sweater.