I don't think you are being particularly realistic here. There is no machine on the planet at this price level with those levels of wave rom, and the other features thrown in.

Each manufacturer has their ways of compressing the rom, so direct comparison with samplers using uncompressed formats is not really comparable.

It sounds like you want something like a Triton with huge hard drive and cd library. Or gigasampler with a low latency drive controller keyboard. Look at the respective prices, and then try a one touch play with accompaniment on those. This isn't apples and pears comparison, this is apples and cheese.