I have now owned four baby sleep sacks.  Started out with the HALO, which seemed nice and soft (so bought the next size up), but it quickly turned out to be stuffy and hot because of their synthetic makeup; then moved on to cotton and finally have been more-or-less happy with a cotton-poly blend, which has kept my baby fairly snug and warm.  My baby is now nine months old and I've been searching for a bigger (and more natural) sleep sack to take her through the next year.  I couldn't decide between the Merino and Woolino (they seem pretty much identical!) but the Merino was on sale, so I thought I'd give it a go.

Unfortunately, shortly after it arrived in the mail, I've decided to return it, for the following reasons:

(1) the Merino 0-2 years size is fairly small, i.e., about as small as the current sleep sack that we're looking to replace (which no longer fits a nine month old).  I acknowledge that at 30 inches my baby is fairly tall, but I can't see most two year olds fitting into this thing;

(2) the Merino has only one arm strap with snaps on it.  This may not seem like a big deal to many parents, but for those who have a baby that's sometimes cranky around bed time, you'll know that putting on PJs or anything else over their heads or through their arms can bring on fits of crying and screaming.  For this reason, we love our current sleep sack, which has snaps on both arm straps so that you can simply sandwich them between the layers and quickly zip and snap closed.  If they're really hot or uncomfortable, or otherwise need a quick release from the sleep sack, you can simply undo the snaps and lift them out.

After returning the Merino, I've decided to do some additional research on the Woolino to make sure it would have what I was after.  Here are the differences I discovered:

- Merino - only one strap opens; Woolino - both open
- Merino length is not adjustable; Woolino can be adjusted for a small baby
- Merino is slightly cheaper, if you compare it to the Woolino organic, but Woolino has an older line of non-organic sleep sacks that are cheaper (on their site)
- Merino has two thicknesses - regular and winter; Woolino has a thicker wool so only offer one thickness
- Merino sizes are: 0-2 yrs: 34 inch, toddler: 42 inch; Woolino 0-2 yrs: 35 inch; toddler: 42inches -- basically the same, with an extra inch on the Woolino for the baby size

In the end, the thicker wool and second opening strap edged Woolino ahead of Merino for me.  I think having an adjustable length is also great if you start using a sleep sack for a wee little one (not an issue for my nine month old at this point).

So I've decided to go for the Woolino.  Seems like a big investment, but given that my baby will sleep in it every night, I think it's worth it.  There was also a $20 discount code for the Woolino (good until January) that I took advantage of, so the price difference wasn't very big in the end!