F3G,
Yes, we agree, old and tired are two different factors, and one is much more likely to affect performance than the other. Old is easily tolerated, and often very sought after. Tired should be tolerated in only very minor amounts. That thin prop, should be replaced, those retarded mags should be retimed, or overhauled, those low cylinders should be replaced, the dented wing really should be properly repaired, (or covered with a STOL kit! That will show you certain performance improvements, and a great safety improvement, though give up spins). Like nearly every machine ever created to perform a task, an aircraft is a consumable. It can be consumed quickly, or slowly. If you're willing to expect a little less performance, you might be able to consume it a little more before you start overhauling and replacing. But, you are still putting away the reserves right?
The aforementioned C207 was approaced by a mechanic, who, from 20 feet away said: "what a piece of junk!" This conclusion was based on really poor paint. I asked him what the defects were, and the only one he could come up with was poor paint, and worn upholstery. It performed well, but he did not know that, he judged an old, tired piece of junk based upon appearance at a distance.
If you're not willing to pay for an aircraft which is well maintained, why are you complaining about poor performance. You get what you pay for...
Pilot DAR