The conrod takes a larger gudgeon pin, so it is somewhat useful when adapting larger 'A'-family pistons, the alternative is to simply machine your regular A12 conrods. This is the most common procedure as A12A conrods are not common.

The combustion chambers are of the performance shape and the cylinder takes a wet manifold. It also has the shared early and late bolt pattern for the inlet manifold. There is some commentary that the conrods are stronger but once again costs to strengthen regular A12 conrods are cheap enough not to warrant sourcing the not-so-plentiful A12A variant.

Not sought after, apart for their novelty factor their isn't much more appeal, perhaps an extra horsepower or so.

Engine is not worth much more than a regular A12 and some people would pay more because of it's novelty, I would.