SoftwareSerial sounds like a great way to free up your HardwareSerial connection to the computer, in example for debugging purposes. But it is a source of grief using it to communicated with the ESP8266. You'll be limited to low speed, and chances are you will loose characters anyways.
My recommendation: Don't do it, it is an avoidable source of self-created troubles. Programming with an ISP is not a big deal, and so is logging with I2C. Check out AC.programmer!