A few non-expert OPINIONS:

Peeling: I think that was fixed before the LA was released.

LA vs others: Some like the weight and parts availability of the LA's as well as the price. Brodak is good, Magnum is good, Fox is good...

424 vs. two: The mail idea is to achieve a steady velocity during the pattern. Having a 424 can do this, and running in two cycle (piped or not) with a flat prop can do this. A four stroke can do this with a big *ss prop.

The higher you get in the PA food chain, the more you are willing to spend big $$ for better metalurgy.

It isn't the engine that makes the top few percent, it is the practice, practice, practice.
BUT, along with (or because of) the practice, many appear to be able to adjust venturis, head shims, and fuel content for whatever engine they use, to suit particular conditions.

Again, this is just one opinion.
George