Luis,
the SD1 has all the most important styles from the X1 and has even many sounds that in the X1 were available only as an option (you had to buy them).
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Korg Kronos 61 and PA3X-Pro76, Roland G-70, BK7-m and Integra 7, Casio PX-5S, Fender Stratocaster with Fralin pickups, Fender Stratocaster with Kinman pickups, vintage Gibson SG standard.