The second nice thing about an add on pump is they put out the same amount of air no matter how fast or slow you run your saw. My Hegner seems to, but all the other saws I have had/have, the slower you run the saw the less air pumped. That is why I keep looking for an "add on" pump for my Ex.
Great find, great great price. I hope it last a good long time. It should, they are built to run for long periods at a time. I wife has an oxygen pump for when she sleeps. It is a much bigger unit, but it does get warm.