I call BS too. I raced quite a bit with a 3s setup in a buggy with a 1512 1.5d (3300kv) motor. It worked pretty well, but the battery temps were pushing 140+ degrees. I eventually puffed a 3s 6000 25c PQ pack and used a 3s 8000 Maxamps pack. There is no way a 3s setup geared to run with nitros on a medium to large track is going to run efficient.

On smaller tracks, 3s is more than adequate though.

I wouldn't say that the motors and esc run dramatically cooler, but the batteries definitely aren't nearly as strained. The batteries on my 5s setup rarely break 100 degrees on a 80 degree day as long as I don't run them down to the LVC. As batteries improve, it may be possible to run lower voltages without much risk though.

The difference is in the efficiency/run time. I can get the same run time out of a 5s 3300 that most guys are getting out of 4s 5000/5500 packs. I know people racing with 6s 2600 packs. I have RACED a full 24 minutes straight during an A Main to LVC on a 5s 5000 pack on a big ass track. There is no way a 3s or 4s setup will ever get that kind of run time.