I wouldn't say they don't care. If you already have a shaky application, a 4 or 8 on the carving may cause them to doubt your file.
You want my advice: go down and write the american dat. If you're from Toronto, drive down to Buffalo - it's only like an hour and a half drive. They don't have the carving, but they have QR (which is fun) and orgo (which is not fun). But I think it's worth it. You can write the american DAT on pretty much any day of the year; schools will see that you're serious about the US, schools may feel more comfortable about you because they can compare you to most applications (esp. orgo); and I personally felt waaay more comfortable doing the exam on a computer. good luck canuck!