The Roland XP's are considered "Semi-weighted" in between non-weighted synth keys and full fledged piano keys..... I don't know if the S30 has this on it. It may just be a worse synth overall but I feel that it is the keys..... It all comes down to whether you like the feel or not, if you don't like the feel of the S30's keys don't buy it (or is it too late?) it will probably drive you nuts.

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John 3:16 For God so loved the world, that He gave His only Son, that whoever believes in Him should not perish, but have everlasting life.