Also, comfort depends a lot on your body type!
If you're interested in a buckle carrier (also called a "soft structured carrier" or SSC) there are quite a lot of options ... the Ergo is just one.
My only complaint about the Ergo is the bulkiness of the infant insert; otherwise it's a great carrier.
Another good option in the buckle carrier category is the Boba 3G, which does not require an infant insert for the newborn stage because the body is adjustable to safely position a baby that cannot sit up. The strap padding isn't as bulky feeling as the Original Ergo, for example, but would be about the same as the Performance. I'm not sure how it would compare to the Sport.
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Liz
DD (3/2010)
"Make mistakes! Get messy!" - Miss Frizzle