It depends on your definition of "cold weather". If you plan to consistently camp below freezing, I would strongly encourage tank heaters.
Truth be told, I have no idea what size heater we have on our current trailer. We used it the first winter, but it gets so unbelievably hot so quickly that we were uncomfortable. Our thermostat apparently wasn't accurate, we could never dial it in right.
We found it was much cheaper, quieter and more comfortable to heat with an electric space heater. We camped in NYC in December of 2011 for a week with an oil filled radiator heating the camper. Temps never got above 30 during the day and got into the teens at night, we were comfortable... until we had to walk to the bath house since we were dry camping.
That brings me back to the tank heaters... You can be nice and warm no matter what heater you have... but if you have to go outside to shower or use the facilities, you will still be cold.
Either way, enjoy your new camper. We love cool/cold weather camping!