AC vs. LC is not a matter of overheating, because both systems will sufficiently cool down the engine. This is prevalent worry of many perspective owners.
However, AC scooters have lower engine output, and considering that on 50 cc 1-1.5 hp is a BIG difference, I would not buy AC one. Deviation from this rule would be OK if I had weight of 100 lbs, or if I drove scoot on short distances in completely flat areas. Considering that I am 240+ and just to reach center of the town 10 kms away I change 400 m of altitude... you get the picture.
I had two 50 cc AC scooters in the past and they were SLOW. Peugeot Zenith and Kymco Cobra cross.
Things change with higher displacement, so I had for example 125 cc air cooled Yamaha/11 hp which was nice, and 750 cc air/oil cooled Kawasaki that was even nicer. But this is a whole different story.