4 or 6 cylinder on an SUV

95% of the time this would only be used for light cargo stuff and family vacations. The other 5% may be used for hooking up a trailer for stuff.
I have a pontiac sunfire now that puts out almost 150hp, this 4 cylindar Escape puts out 153hp and the curbisde weight is about 500lbs heavier. Acceleration is not a big concern of mine. Just trying to really figure out why someone would say that a 6 cylindar would be the better engine. I could see if I was towing or racing but I will be neither. Will the extra 500lbs really tax a 4 cylindar engine?
Thanks Again.