Boy, This is like a mine field waiting for the uninformed to take an errant step!
First of all, a simple answer to the original question. The reason the OS .25 et all have been getting so many rave reviews is that they are a pretty near perfect modern equivilant powerwise to the historic king, the Fox .35...without a lot of the baggage that comes with side mounting, special fuels, careful break-in etc. If you can build any of the modern (or not so modern) profiles straight and at a reasonable weight and out of the box .20/.25 OS or LA provides a bunch of useable power with very little fiddling and little risk of hurting the engine while learning the dos and don'ts of running it.
Top level competition stunt is another animal entirely and replete with lots of considerations beyond "mere" functionality. It is absolutely true that under ideal conditions combos such as my Chizler/Max 35S or Billy's VSC dominating Vulcan and Aero Tiger .36 can fly patterns at the highest level. There is NO magic that makes bigger airplanes and bigger engines and/or pipes/four cycles inherently better mechanisms for performing the pattern than smaller/simpler/less powerful combinations.
This is, yet again, another rendition of the often debated better mousetrap definition of CLPA. Sometimes its a debate about one design versus another or, more often like this, one of motive superiority of one sort or another. The bottom line in almost any clash of top pilots is that the pilot whose powertrain performs most to the liking of its pilot will likely come out on top.
It doesn;t make a lot of difference what form that powertrain takes, only that it performs in the manner desired and that the elements at the time of competition are receptive to that type of power delivery. Under a given set of conditions almost any well tuned combintion is capable of performing excellently.
In a subjectively evaluated event such as ours, however, other aspects come into play, Not the least of these is the awareness on the part of the evaluators (judges) of just exactly what is "state of the art" in the technical areas. It is entirely possible that either the judges expect top level competitors to use state of the art systems or, conversely, that competitors "expect judges to expect" that and thus they tend to run in packs, all using the "expected" high tech approach.
Recent history tends to support the latter thesis inasmuch as the judges at the last two nats and team trials seemed entirely willing to give high marks to a decidedly "non-high-zoot" plane/pilot/powertrain presentation in the form of young Todd Lee, his modified Sig kit and non-piped 4/2/4 OS .46SF.
These comments obviously open up a vast arena of possible opinions about which I have no desire to initiate debate. On the other hand, I'll gladly sit back and see what others have to say.
