The reason I suggested the LA 25 to the Reading club was that we'd found in combat that the stock LA 25 and a good, stock Fox 35 were virtually identical is performance. It seemed to make sense to extend the Foxberg concept to another engine that is also readily available and has a few other nice features.
Don't doubt it though, if you get couple dedicated racers into it, they will learn how to fine tune an LA 25 and get more speed out of it. Just like a stock Fox. Careful selection of parts, getting exactly the right fits in the right spots, head clearance, squish band, etc. It may be a little harder with the LA's though because OS makes the parts to very tight tolerances.