There is not a good SSC IMO that works for newborns and toddlers both. It's just the nature of buckles and having structure. If it's small enough to work for a newborn well, it's going to be too small for a toddler and vice versa.
There is the Ergo that has an infant insert that has to be used for the first few months. I personally think the insert is annoying and then you can't BF with the insert and such if that's important to you.
There is also an infant adjustable KinderPack which works for smaller babies (not newborns, but small babies) and can be used up to 18 months before it's outgrown.
Keep in mind most babywearing experts do not support facing out (which is why you see less and less of it with good carriers). It's not a great position for babies. They can't turn away from stimulation and in order to face out, they're not being probably positioned at the hips most of the time. Plus, it puts a lot of extra strain on the parents back - ouch!
If you want a carrier that can last from newborn through toddlerhood consider a woven wrap (BBSlen, Didymos, and such). Higher learning curve, but it will not be outgrown till probably school age. Not sure where you are in Ontario, but there are BWing groups there! They're a great resource for help!
Another carrier suggestion is the mei tai. You can manipulate the carrier to work with newborns (not as ideal as wrapping, but it works) and can use it usually to 2-3 years old depending on the body size. I find an unpadded mei tai hurts my shoulders in a back carry now that DS is older, but it's still a great front carrier. I like that I can do high back carries in it around 4 months, so DS could see over my shoulder (a good compromise to facing out). My padded mei tai (like Beanslings, Bamberoo, and KinderCarry) is still VERY comfortable in a back carry.
Ring sling is another option that is a great newborn carrier and is good for toddler ups and downs. It is just a one shoulder carry though, so I can't wear DS for hours like I can with other carriers. Usually 30 minutes is my max at his age.
Let me know if you have any more questions. I could talk alllllll day about BWing.