[Jeff Lee]

Simple test. Run your GT/AA right off the trailer 3 runs in a row without stopping to cool it down between runs. By the time it's 220 degrees it should slow down considerably, right?
Now take it to the cool down area at your track. Run clean / cool water through the system, get it down to 50 degrees if you can. Then make a run. Is it faster?
That's your answer. No opinions, no claims, no money out of pocket, just see for yourself.
These chillers will get your engine water temp down to around 50 degrees quickly. Without a chiller, the ambient temperature may keep you from getting below 80-90 on some days (I live in AZ). You can make one out of an ice chest on the cheap. On a professional looking level, the one offered by Advanced Clutches is around $700. The most expensive I've seen are close to $1500.
That's quite a spread and I can't imagine one does a better job than the other.
You'll also save battery drain as you wont have to run your electric water pump and electric fan trying to cool down between rounds. I think we've all lost a round because your battery was lower than you thought.