I sent a small packet to Australia and it took 13 days to get from Swansea to Heathrow, sat in Heathrow for 9 days before leaving the country, then sat at Brisbane airport for 7 days before being processed on Wednesday. Waiting for it to be actually delivered now!
If you are planning to live full time in Thailand there are no real advantages to the Non O-A but a huge disadvantage in that it requires specific Health Insurance for each Extension of Stay.
If you are planning to travel between your home country and Thailand on a regular basis then the Non O-A might have advantages in certain situations.