Naso, nothing personal, but I think your wrong.
Short term maximum speed is what usually determines if you can extend and exit a fight or not.
Most people I know, keep their WEP (at least the BnZ pilots of whom we are speaking) for the purpose of the extension.
The only time you see that "long chase" of which you speak, is if two similar plane types are fighting, or those rare cases where two different aircraft have similar performance at a particular altitude.
Otherwise, even with a small difference in speed, acceleration, or initial E state , the matter is quickly ended with the death of the defending pilot, or he extends enough distance to make it back to friendly aircraft which can cover him.
In 9 out of 10 of my "long chase" situations, its actually a case of me intentionally keeping the seperation just close enough to keep the chasing pilot interested to drag him to a friend for an easy kill.
Just my opinon though

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Vermillion
**MOL**, Men of Leisure
"Real Men fly Radials, Nancy Boys fly Spitfires"