Hi.
We have the Heron wall mounted unit. It warms up enough for us but we also take a small blower heater. As an aircon I have had it running at 44 deg in Adelaide and it coped very well.
Minuses - it takes up space that would normally be used for the microwave, so we put our microwave under the cooktop instead of an oven - we didn't want an oven.
Plusses - it is about $1,000 ish cheaper than the roof mount and keeps your profile lower for towing / storage. Some say they make a pop top heavier to lift but I can't comment on that cause I've never used a roof with an aircon on it.
Hope this helps - all comes down to personal choice and budget.
lots of great fact. thanks for the help in making my choice. cheers fellas happy travells